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docs: blockdev: convert to ReST

Browse Source 
Rename the blockdev documentation files to ReST, add an
index for them and adjust in order to produce a nice html
output via the Sphinx build system.

The drbd sub-directory contains some graphs and data flows.
Add those too to the documentation.

At its new index.rst, let's add a :orphan: while this is not linked to
the main index.rst file, in order to avoid build warnings.

Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
This commit is contained in:
Mauro Carvalho Chehab 2019-04-18 17:29:24 -03:00
parent e0ae154404
commit 39443104c7
15 changed files with 398 additions and 245 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
Documentation/admin-guide/kernel-parameters.txt
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@ -1249,7 +1249,7 @@
See also Documentation/fault-injection/. See also Documentation/fault-injection/.
floppy= [HW] floppy= [HW]
See Documentation/blockdev/floppy.txt. See Documentation/blockdev/floppy.rst.
force_pal_cache_flush force_pal_cache_flush
[IA-64] Avoid check_sal_cache_flush which may hang on [IA-64] Avoid check_sal_cache_flush which may hang on
@ -2234,7 +2234,7 @@
memblock=debug [KNL] Enable memblock debug messages. memblock=debug [KNL] Enable memblock debug messages.
load_ramdisk= [RAM] List of ramdisks to load from floppy load_ramdisk= [RAM] List of ramdisks to load from floppy
See Documentation/blockdev/ramdisk.txt. See Documentation/blockdev/ramdisk.rst.
lockd.nlm_grace_period=P [NFS] Assign grace period. lockd.nlm_grace_period=P [NFS] Assign grace period.
Format: <integer> Format: <integer>
@ -3268,7 +3268,7 @@
pcd. [PARIDE] pcd. [PARIDE]
See header of drivers/block/paride/pcd.c. See header of drivers/block/paride/pcd.c.
See also Documentation/blockdev/paride.txt. See also Documentation/blockdev/paride.rst.
pci=option[,option...] [PCI] various PCI subsystem options. pci=option[,option...] [PCI] various PCI subsystem options.
@ -3512,7 +3512,7 @@
needed on a platform with proper driver support. needed on a platform with proper driver support.
pd. [PARIDE] pd. [PARIDE]
See Documentation/blockdev/paride.txt. See Documentation/blockdev/paride.rst.
pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at
boot time. boot time.
@ -3527,10 +3527,10 @@
and performance comparison. and performance comparison.
pf. [PARIDE] pf. [PARIDE]
See Documentation/blockdev/paride.txt. See Documentation/blockdev/paride.rst.
pg. [PARIDE] pg. [PARIDE]
See Documentation/blockdev/paride.txt. See Documentation/blockdev/paride.rst.
pirq= [SMP,APIC] Manual mp-table setup pirq= [SMP,APIC] Manual mp-table setup
See Documentation/x86/i386/IO-APIC.rst. See Documentation/x86/i386/IO-APIC.rst.
@ -3642,7 +3642,7 @@
prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
before loading. before loading.
See Documentation/blockdev/ramdisk.txt. See Documentation/blockdev/ramdisk.rst.
psi= [KNL] Enable or disable pressure stall information psi= [KNL] Enable or disable pressure stall information
tracking. tracking.
@ -3664,7 +3664,7 @@
pstore.backend= Specify the name of the pstore backend to use pstore.backend= Specify the name of the pstore backend to use
pt. [PARIDE] pt. [PARIDE]
See Documentation/blockdev/paride.txt. See Documentation/blockdev/paride.rst.
pti= [X86_64] Control Page Table Isolation of user and pti= [X86_64] Control Page Table Isolation of user and
kernel address spaces. Disabling this feature kernel address spaces. Disabling this feature
@ -3693,7 +3693,7 @@
See Documentation/admin-guide/md.rst. See Documentation/admin-guide/md.rst.
ramdisk_size= [RAM] Sizes of RAM disks in kilobytes ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
See Documentation/blockdev/ramdisk.txt. See Documentation/blockdev/ramdisk.rst.
random.trust_cpu={on,off} random.trust_cpu={on,off}
[KNL] Enable or disable trusting the use of the [KNL] Enable or disable trusting the use of the

6
Documentation/blockdev/drbd/data-structure-v9.txt → Documentation/blockdev/drbd/data-structure-v9.rst
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@ -1,3 +1,7 @@
================================
kernel data structure for DRBD-9
================================
This describes the in kernel data structure for DRBD-9. Starting with This describes the in kernel data structure for DRBD-9. Starting with
Linux v3.14 we are reorganizing DRBD to use this data structure. Linux v3.14 we are reorganizing DRBD to use this data structure.
@ -10,7 +14,7 @@ device is represented by a block device locally.
The DRBD objects are interconnected to form a matrix as depicted below; a The DRBD objects are interconnected to form a matrix as depicted below; a
drbd_peer_device object sits at each intersection between a drbd_device and a drbd_peer_device object sits at each intersection between a drbd_device and a
drbd_connection: drbd_connection::
/--------------+---------------+.....+---------------\ /--------------+---------------+.....+---------------\
| resource | device | | device | | resource | device | | device |

28
Documentation/blockdev/drbd/figures.rst Normal file
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@ -0,0 +1,28 @@
.. The here included files are intended to help understand the implementation
Data flows that Relate some functions, and write packets
========================================================
.. kernel-figure:: DRBD-8.3-data-packets.svg
:alt: DRBD-8.3-data-packets.svg
:align: center
.. kernel-figure:: DRBD-data-packets.svg
:alt: DRBD-data-packets.svg
:align: center
Sub graphs of DRBD's state transitions
======================================
.. kernel-figure:: conn-states-8.dot
:alt: conn-states-8.dot
:align: center
.. kernel-figure:: disk-states-8.dot
:alt: disk-states-8.dot
:align: center
.. kernel-figure:: node-states-8.dot
:alt: node-states-8.dot
:align: center

15
Documentation/blockdev/drbd/README.txt → Documentation/blockdev/drbd/index.rst
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@ -1,4 +1,9 @@
==========================================
Distributed Replicated Block Device - DRBD
==========================================
Description Description
===========
DRBD is a shared-nothing, synchronously replicated block device. It DRBD is a shared-nothing, synchronously replicated block device. It
is designed to serve as a building block for high availability is designed to serve as a building block for high availability
@ -7,10 +12,8 @@ Description
Please visit http://www.drbd.org to find out more. Please visit http://www.drbd.org to find out more.
The here included files are intended to help understand the implementation .. toctree::
:maxdepth: 1
DRBD-8.3-data-packets.svg, DRBD-data-packets.svg data-structure-v9
relates some functions, and write packets. figures
conn-states-8.dot, disk-states-8.dot, node-states-8.dot
The sub graphs of DRBD's state transitions

88
Documentation/blockdev/floppy.txt → Documentation/blockdev/floppy.rst
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@ -1,35 +1,37 @@
This file describes the floppy driver. =============
Floppy Driver
=============
FAQ list: FAQ list:
========= =========
A FAQ list may be found in the fdutils package (see below), and also A FAQ list may be found in the fdutils package (see below), and also
at <http://fdutils.linux.lu/faq.html>. at <http://fdutils.linux.lu/faq.html>.
LILO configuration options (Thinkpad users, read this) LILO configuration options (Thinkpad users, read this)
====================================================== ======================================================
The floppy driver is configured using the 'floppy=' option in The floppy driver is configured using the 'floppy=' option in
lilo. This option can be typed at the boot prompt, or entered in the lilo. This option can be typed at the boot prompt, or entered in the
lilo configuration file. lilo configuration file.
Example: If your kernel is called linux-2.6.9, type the following line Example: If your kernel is called linux-2.6.9, type the following line
at the lilo boot prompt (if you have a thinkpad): at the lilo boot prompt (if you have a thinkpad)::
linux-2.6.9 floppy=thinkpad linux-2.6.9 floppy=thinkpad
You may also enter the following line in /etc/lilo.conf, in the description You may also enter the following line in /etc/lilo.conf, in the description
of linux-2.6.9: of linux-2.6.9::
append = "floppy=thinkpad" append = "floppy=thinkpad"
Several floppy related options may be given, example: Several floppy related options may be given, example::
linux-2.6.9 floppy=daring floppy=two_fdc linux-2.6.9 floppy=daring floppy=two_fdc
append = "floppy=daring floppy=two_fdc" append = "floppy=daring floppy=two_fdc"
If you give options both in the lilo config file and on the boot If you give options both in the lilo config file and on the boot
prompt, the option strings of both places are concatenated, the boot prompt, the option strings of both places are concatenated, the boot
prompt options coming last. That's why there are also options to prompt options coming last. That's why there are also options to
restore the default behavior. restore the default behavior.
@ -38,21 +40,23 @@ restore the default behavior.
Module configuration options Module configuration options
============================ ============================
If you use the floppy driver as a module, use the following syntax: If you use the floppy driver as a module, use the following syntax::
modprobe floppy floppy="<options>"
Example: modprobe floppy floppy="<options>"
modprobe floppy floppy="omnibook messages"
If you need certain options enabled every time you load the floppy driver, Example::
you can put:
options floppy floppy="omnibook messages" modprobe floppy floppy="omnibook messages"
If you need certain options enabled every time you load the floppy driver,
you can put::
options floppy floppy="omnibook messages"
in a configuration file in /etc/modprobe.d/. in a configuration file in /etc/modprobe.d/.
The floppy driver related options are: The floppy driver related options are:
floppy=asus_pci floppy=asus_pci
Sets the bit mask to allow only units 0 and 1. (default) Sets the bit mask to allow only units 0 and 1. (default)
@ -70,8 +74,7 @@ in a configuration file in /etc/modprobe.d/.
Tells the floppy driver that you have only one floppy controller. Tells the floppy driver that you have only one floppy controller.
(default) (default)
floppy=two_fdc floppy=two_fdc / floppy=<address>,two_fdc
floppy=<address>,two_fdc
Tells the floppy driver that you have two floppy controllers. Tells the floppy driver that you have two floppy controllers.
The second floppy controller is assumed to be at <address>. The second floppy controller is assumed to be at <address>.
This option is not needed if the second controller is at address This option is not needed if the second controller is at address
@ -84,8 +87,7 @@ in a configuration file in /etc/modprobe.d/.
floppy=0,thinkpad floppy=0,thinkpad
Tells the floppy driver that you don't have a Thinkpad. Tells the floppy driver that you don't have a Thinkpad.
floppy=omnibook floppy=omnibook / floppy=nodma
floppy=nodma
Tells the floppy driver not to use Dma for data transfers. Tells the floppy driver not to use Dma for data transfers.
This is needed on HP Omnibooks, which don't have a workable This is needed on HP Omnibooks, which don't have a workable
DMA channel for the floppy driver. This option is also useful DMA channel for the floppy driver. This option is also useful
@ -144,14 +146,16 @@ in a configuration file in /etc/modprobe.d/.
described in the physical CMOS), or if your BIOS uses described in the physical CMOS), or if your BIOS uses
non-standard CMOS types. The CMOS types are: non-standard CMOS types. The CMOS types are:
0 - Use the value of the physical CMOS == ==================================
1 - 5 1/4 DD 0 Use the value of the physical CMOS
2 - 5 1/4 HD 1 5 1/4 DD
3 - 3 1/2 DD 2 5 1/4 HD
4 - 3 1/2 HD 3 3 1/2 DD
5 - 3 1/2 ED 4 3 1/2 HD
6 - 3 1/2 ED 5 3 1/2 ED
16 - unknown or not installed 6 3 1/2 ED
16 unknown or not installed
== ==================================
(Note: there are two valid types for ED drives. This is because 5 was (Note: there are two valid types for ED drives. This is because 5 was
initially chosen to represent floppy *tapes*, and 6 for ED drives. initially chosen to represent floppy *tapes*, and 6 for ED drives.
@ -162,8 +166,7 @@ in a configuration file in /etc/modprobe.d/.
Print a warning message when an unexpected interrupt is received. Print a warning message when an unexpected interrupt is received.
(default) (default)
floppy=no_unexpected_interrupts floppy=no_unexpected_interrupts / floppy=L40SX
floppy=L40SX
Don't print a message when an unexpected interrupt is received. This Don't print a message when an unexpected interrupt is received. This
is needed on IBM L40SX laptops in certain video modes. (There seems is needed on IBM L40SX laptops in certain video modes. (There seems
to be an interaction between video and floppy. The unexpected to be an interaction between video and floppy. The unexpected
@ -199,47 +202,54 @@ in a configuration file in /etc/modprobe.d/.
Sets the floppy DMA channel to <nr> instead of 2. Sets the floppy DMA channel to <nr> instead of 2.
floppy=slow floppy=slow
Use PS/2 stepping rate: Use PS/2 stepping rate::
" PS/2 floppies have much slower step rates than regular floppies.
PS/2 floppies have much slower step rates than regular floppies.
It's been recommended that take about 1/4 of the default speed It's been recommended that take about 1/4 of the default speed
in some more extreme cases." in some more extreme cases.
Supporting utilities and additional documentation: Supporting utilities and additional documentation:
================================================== ==================================================
Additional parameters of the floppy driver can be configured at Additional parameters of the floppy driver can be configured at
runtime. Utilities which do this can be found in the fdutils package. runtime. Utilities which do this can be found in the fdutils package.
This package also contains a new version of mtools which allows to This package also contains a new version of mtools which allows to
access high capacity disks (up to 1992K on a high density 3 1/2 disk!). access high capacity disks (up to 1992K on a high density 3 1/2 disk!).
It also contains additional documentation about the floppy driver. It also contains additional documentation about the floppy driver.
The latest version can be found at fdutils homepage: The latest version can be found at fdutils homepage:
http://fdutils.linux.lu http://fdutils.linux.lu
The fdutils releases can be found at: The fdutils releases can be found at:
http://fdutils.linux.lu/download.html http://fdutils.linux.lu/download.html
http://www.tux.org/pub/knaff/fdutils/ http://www.tux.org/pub/knaff/fdutils/
ftp://metalab.unc.edu/pub/Linux/utils/disk-management/ ftp://metalab.unc.edu/pub/Linux/utils/disk-management/
Reporting problems about the floppy driver Reporting problems about the floppy driver
========================================== ==========================================
If you have a question or a bug report about the floppy driver, mail If you have a question or a bug report about the floppy driver, mail
me at Alain.Knaff@poboxes.com . If you post to Usenet, preferably use me at Alain.Knaff@poboxes.com . If you post to Usenet, preferably use
comp.os.linux.hardware. As the volume in these groups is rather high, comp.os.linux.hardware. As the volume in these groups is rather high,
be sure to include the word "floppy" (or "FLOPPY") in the subject be sure to include the word "floppy" (or "FLOPPY") in the subject
line. If the reported problem happens when mounting floppy disks, be line. If the reported problem happens when mounting floppy disks, be
sure to mention also the type of the filesystem in the subject line. sure to mention also the type of the filesystem in the subject line.
Be sure to read the FAQ before mailing/posting any bug reports! Be sure to read the FAQ before mailing/posting any bug reports!
Alain Alain
Changelog Changelog
========= =========
10-30-2004 : Cleanup, updating, add reference to module configuration. 10-30-2004 :
Cleanup, updating, add reference to module configuration.
James Nelson <james4765@gmail.com> James Nelson <james4765@gmail.com>
6-3-2000 : Original Document 6-3-2000 :
Original Document

16
Documentation/blockdev/index.rst Normal file
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@ -0,0 +1,16 @@
:orphan:
===========================
The Linux RapidIO Subsystem
===========================
.. toctree::
:maxdepth: 1
floppy
nbd
paride
ramdisk
zram
drbd/index

2
Documentation/blockdev/nbd.txt → Documentation/blockdev/nbd.rst
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@ -1,3 +1,4 @@
==================================
Network Block Device (TCP version) Network Block Device (TCP version)
================================== ==================================
@ -28,4 +29,3 @@ max_part
nbds_max nbds_max
Number of block devices that should be initialized (default: 16). Number of block devices that should be initialized (default: 16).

194
Documentation/blockdev/paride.txt → Documentation/blockdev/paride.rst
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@ -1,15 +1,17 @@
===================================
Linux and parallel port IDE devices Linux and parallel port IDE devices
===================================
PARIDE v1.03 (c) 1997-8 Grant Guenther <grant@torque.net> PARIDE v1.03 (c) 1997-8 Grant Guenther <grant@torque.net>
1. Introduction 1. Introduction
===============
Owing to the simplicity and near universality of the parallel port interface Owing to the simplicity and near universality of the parallel port interface
to personal computers, many external devices such as portable hard-disk, to personal computers, many external devices such as portable hard-disk,
CD-ROM, LS-120 and tape drives use the parallel port to connect to their CD-ROM, LS-120 and tape drives use the parallel port to connect to their
host computer. While some devices (notably scanners) use ad-hoc methods host computer. While some devices (notably scanners) use ad-hoc methods
to pass commands and data through the parallel port interface, most to pass commands and data through the parallel port interface, most
external devices are actually identical to an internal model, but with external devices are actually identical to an internal model, but with
a parallel-port adapter chip added in. Some of the original parallel port a parallel-port adapter chip added in. Some of the original parallel port
adapters were little more than mechanisms for multiplexing a SCSI bus. adapters were little more than mechanisms for multiplexing a SCSI bus.
@ -28,47 +30,50 @@ were to open up a parallel port CD-ROM drive, for instance, one would
find a standard ATAPI CD-ROM drive, a power supply, and a single adapter find a standard ATAPI CD-ROM drive, a power supply, and a single adapter
that interconnected a standard PC parallel port cable and a standard that interconnected a standard PC parallel port cable and a standard
IDE cable. It is usually possible to exchange the CD-ROM device with IDE cable. It is usually possible to exchange the CD-ROM device with
any other device using the IDE interface. any other device using the IDE interface.
The document describes the support in Linux for parallel port IDE The document describes the support in Linux for parallel port IDE
devices. It does not cover parallel port SCSI devices, "ditto" tape devices. It does not cover parallel port SCSI devices, "ditto" tape
drives or scanners. Many different devices are supported by the drives or scanners. Many different devices are supported by the
parallel port IDE subsystem, including: parallel port IDE subsystem, including:
MicroSolutions backpack CD-ROM - MicroSolutions backpack CD-ROM
MicroSolutions backpack PD/CD - MicroSolutions backpack PD/CD
MicroSolutions backpack hard-drives - MicroSolutions backpack hard-drives
MicroSolutions backpack 8000t tape drive - MicroSolutions backpack 8000t tape drive
SyQuest EZ-135, EZ-230 & SparQ drives - SyQuest EZ-135, EZ-230 & SparQ drives
Avatar Shark - Avatar Shark
Imation Superdisk LS-120 - Imation Superdisk LS-120
Maxell Superdisk LS-120 - Maxell Superdisk LS-120
FreeCom Power CD - FreeCom Power CD
Hewlett-Packard 5GB and 8GB tape drives - Hewlett-Packard 5GB and 8GB tape drives
Hewlett-Packard 7100 and 7200 CD-RW drives - Hewlett-Packard 7100 and 7200 CD-RW drives
as well as most of the clone and no-name products on the market. as well as most of the clone and no-name products on the market.
To support such a wide range of devices, PARIDE, the parallel port IDE To support such a wide range of devices, PARIDE, the parallel port IDE
subsystem, is actually structured in three parts. There is a base subsystem, is actually structured in three parts. There is a base
paride module which provides a registry and some common methods for paride module which provides a registry and some common methods for
accessing the parallel ports. The second component is a set of accessing the parallel ports. The second component is a set of
high-level drivers for each of the different types of supported devices: high-level drivers for each of the different types of supported devices:
=== =============
pd IDE disk pd IDE disk
pcd ATAPI CD-ROM pcd ATAPI CD-ROM
pf ATAPI disk pf ATAPI disk
pt ATAPI tape pt ATAPI tape
pg ATAPI generic pg ATAPI generic
=== =============
(Currently, the pg driver is only used with CD-R drives). (Currently, the pg driver is only used with CD-R drives).
The high-level drivers function according to the relevant standards. The high-level drivers function according to the relevant standards.
The third component of PARIDE is a set of low-level protocol drivers The third component of PARIDE is a set of low-level protocol drivers
for each of the parallel port IDE adapter chips. Thanks to the interest for each of the parallel port IDE adapter chips. Thanks to the interest
and encouragement of Linux users from many parts of the world, and encouragement of Linux users from many parts of the world,
support is available for almost all known adapter protocols: support is available for almost all known adapter protocols:
==== ====================================== ====
aten ATEN EH-100 (HK) aten ATEN EH-100 (HK)
bpck Microsolutions backpack (US) bpck Microsolutions backpack (US)
comm DataStor (old-type) "commuter" adapter (TW) comm DataStor (old-type) "commuter" adapter (TW)
@ -83,9 +88,11 @@ support is available for almost all known adapter protocols:
ktti KT Technology PHd adapter (SG) ktti KT Technology PHd adapter (SG)
on20 OnSpec 90c20 (US) on20 OnSpec 90c20 (US)
on26 OnSpec 90c26 (US) on26 OnSpec 90c26 (US)
==== ====================================== ====
2. Using the PARIDE subsystem 2. Using the PARIDE subsystem
=============================
While configuring the Linux kernel, you may choose either to build While configuring the Linux kernel, you may choose either to build
the PARIDE drivers into your kernel, or to build them as modules. the PARIDE drivers into your kernel, or to build them as modules.
@ -94,10 +101,10 @@ In either case, you will need to select "Parallel port IDE device support"
as well as at least one of the high-level drivers and at least one as well as at least one of the high-level drivers and at least one
of the parallel port communication protocols. If you do not know of the parallel port communication protocols. If you do not know
what kind of parallel port adapter is used in your drive, you could what kind of parallel port adapter is used in your drive, you could
begin by checking the file names and any text files on your DOS begin by checking the file names and any text files on your DOS
installation floppy. Alternatively, you can look at the markings on installation floppy. Alternatively, you can look at the markings on
the adapter chip itself. That's usually sufficient to identify the the adapter chip itself. That's usually sufficient to identify the
correct device. correct device.
You can actually select all the protocol modules, and allow the PARIDE You can actually select all the protocol modules, and allow the PARIDE
subsystem to try them all for you. subsystem to try them all for you.
@ -105,8 +112,9 @@ subsystem to try them all for you.
For the "brand-name" products listed above, here are the protocol For the "brand-name" products listed above, here are the protocol
and high-level drivers that you would use: and high-level drivers that you would use:
================ ============ ====== ========
Manufacturer Model Driver Protocol Manufacturer Model Driver Protocol
================ ============ ====== ========
MicroSolutions CD-ROM pcd bpck MicroSolutions CD-ROM pcd bpck
MicroSolutions PD drive pf bpck MicroSolutions PD drive pf bpck
MicroSolutions hard-drive pd bpck MicroSolutions hard-drive pd bpck
@ -119,8 +127,10 @@ and high-level drivers that you would use:
Hewlett-Packard 5GB Tape pt epat Hewlett-Packard 5GB Tape pt epat
Hewlett-Packard 7200e (CD) pcd epat Hewlett-Packard 7200e (CD) pcd epat
Hewlett-Packard 7200e (CD-R) pg epat Hewlett-Packard 7200e (CD-R) pg epat
================ ============ ====== ========
2.1 Configuring built-in drivers 2.1 Configuring built-in drivers
---------------------------------
We recommend that you get to know how the drivers work and how to We recommend that you get to know how the drivers work and how to
configure them as loadable modules, before attempting to compile a configure them as loadable modules, before attempting to compile a
@ -143,7 +153,7 @@ protocol identification number and, for some devices, the drive's
chain ID. While your system is booting, a number of messages are chain ID. While your system is booting, a number of messages are
displayed on the console. Like all such messages, they can be displayed on the console. Like all such messages, they can be
reviewed with the 'dmesg' command. Among those messages will be reviewed with the 'dmesg' command. Among those messages will be
some lines like: some lines like::
paride: bpck registered as protocol 0 paride: bpck registered as protocol 0
paride: epat registered as protocol 1 paride: epat registered as protocol 1
@ -158,10 +168,10 @@ the last two digits of the drive's serial number (but read MicroSolutions'
documentation about this). documentation about this).
As an example, let's assume that you have a MicroSolutions PD/CD drive As an example, let's assume that you have a MicroSolutions PD/CD drive
with unit ID number 36 connected to the parallel port at 0x378, a SyQuest with unit ID number 36 connected to the parallel port at 0x378, a SyQuest
EZ-135 connected to the chained port on the PD/CD drive and also an EZ-135 connected to the chained port on the PD/CD drive and also an
Imation Superdisk connected to port 0x278. You could give the following Imation Superdisk connected to port 0x278. You could give the following
options on your boot command: options on your boot command::
pd.drive0=0x378,1 pf.drive0=0x278,1 pf.drive1=0x378,0,36 pd.drive0=0x378,1 pf.drive0=0x278,1 pf.drive1=0x378,0,36
@ -169,24 +179,27 @@ In the last option, pf.drive1 configures device /dev/pf1, the 0x378
is the parallel port base address, the 0 is the protocol registration is the parallel port base address, the 0 is the protocol registration
number and 36 is the chain ID. number and 36 is the chain ID.
Please note: while PARIDE will work both with and without the Please note: while PARIDE will work both with and without the
PARPORT parallel port sharing system that is included by the PARPORT parallel port sharing system that is included by the
"Parallel port support" option, PARPORT must be included and enabled "Parallel port support" option, PARPORT must be included and enabled
if you want to use chains of devices on the same parallel port. if you want to use chains of devices on the same parallel port.
2.2 Loading and configuring PARIDE as modules 2.2 Loading and configuring PARIDE as modules
----------------------------------------------
It is much faster and simpler to get to understand the PARIDE drivers It is much faster and simpler to get to understand the PARIDE drivers
if you use them as loadable kernel modules. if you use them as loadable kernel modules.
Note 1: using these drivers with the "kerneld" automatic module loading Note 1:
system is not recommended for beginners, and is not documented here. using these drivers with the "kerneld" automatic module loading
system is not recommended for beginners, and is not documented here.
Note 2: if you build PARPORT support as a loadable module, PARIDE must Note 2:
also be built as loadable modules, and PARPORT must be loaded before the if you build PARPORT support as a loadable module, PARIDE must
PARIDE modules. also be built as loadable modules, and PARPORT must be loaded before
the PARIDE modules.
To use PARIDE, you must begin by To use PARIDE, you must begin by::
insmod paride insmod paride
@ -195,8 +208,8 @@ among other tasks.
Then, load as many of the protocol modules as you think you might need. Then, load as many of the protocol modules as you think you might need.
As you load each module, it will register the protocols that it supports, As you load each module, it will register the protocols that it supports,
and print a log message to your kernel log file and your console. For and print a log message to your kernel log file and your console. For
example: example::
# insmod epat # insmod epat
paride: epat registered as protocol 0 paride: epat registered as protocol 0
@ -205,22 +218,22 @@ example:
paride: k971 registered as protocol 2 paride: k971 registered as protocol 2
Finally, you can load high-level drivers for each kind of device that Finally, you can load high-level drivers for each kind of device that
you have connected. By default, each driver will autoprobe for a single you have connected. By default, each driver will autoprobe for a single
device, but you can support up to four similar devices by giving their device, but you can support up to four similar devices by giving their
individual co-ordinates when you load the driver. individual co-ordinates when you load the driver.
For example, if you had two no-name CD-ROM drives both using the For example, if you had two no-name CD-ROM drives both using the
KingByte KBIC-951A adapter, one on port 0x378 and the other on 0x3bc KingByte KBIC-951A adapter, one on port 0x378 and the other on 0x3bc
you could give the following command: you could give the following command::
# insmod pcd drive0=0x378,1 drive1=0x3bc,1 # insmod pcd drive0=0x378,1 drive1=0x3bc,1
For most adapters, giving a port address and protocol number is sufficient, For most adapters, giving a port address and protocol number is sufficient,
but check the source files in linux/drivers/block/paride for more but check the source files in linux/drivers/block/paride for more
information. (Hopefully someone will write some man pages one day !). information. (Hopefully someone will write some man pages one day !).
As another example, here's what happens when PARPORT is installed, and As another example, here's what happens when PARPORT is installed, and
a SyQuest EZ-135 is attached to port 0x378: a SyQuest EZ-135 is attached to port 0x378::
# insmod paride # insmod paride
paride: version 1.0 installed paride: version 1.0 installed
@ -237,46 +250,47 @@ Note that the last line is the output from the generic partition table
scanner - in this case it reports that it has found a disk with one partition. scanner - in this case it reports that it has found a disk with one partition.
2.3 Using a PARIDE device 2.3 Using a PARIDE device
--------------------------
Once the drivers have been loaded, you can access PARIDE devices in the Once the drivers have been loaded, you can access PARIDE devices in the
same way as their traditional counterparts. You will probably need to same way as their traditional counterparts. You will probably need to
create the device "special files". Here is a simple script that you can create the device "special files". Here is a simple script that you can
cut to a file and execute: cut to a file and execute::
#!/bin/bash #!/bin/bash
# #
# mkd -- a script to create the device special files for the PARIDE subsystem # mkd -- a script to create the device special files for the PARIDE subsystem
# #
function mkdev { function mkdev {
mknod $1 $2 $3 $4 ; chmod 0660 $1 ; chown root:disk $1 mknod $1 $2 $3 $4 ; chmod 0660 $1 ; chown root:disk $1
} }
# #
function pd { function pd {
D=$( printf \\$( printf "x%03x" $[ $1 + 97 ] ) ) D=$( printf \\$( printf "x%03x" $[ $1 + 97 ] ) )
mkdev pd$D b 45 $[ $1 * 16 ] mkdev pd$D b 45 $[ $1 * 16 ]
for P in 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 for P in 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
do mkdev pd$D$P b 45 $[ $1 * 16 + $P ] do mkdev pd$D$P b 45 $[ $1 * 16 + $P ]
done done
} }
# #
cd /dev cd /dev
# #
for u in 0 1 2 3 ; do pd $u ; done for u in 0 1 2 3 ; do pd $u ; done
for u in 0 1 2 3 ; do mkdev pcd$u b 46 $u ; done for u in 0 1 2 3 ; do mkdev pcd$u b 46 $u ; done
for u in 0 1 2 3 ; do mkdev pf$u b 47 $u ; done for u in 0 1 2 3 ; do mkdev pf$u b 47 $u ; done
for u in 0 1 2 3 ; do mkdev pt$u c 96 $u ; done for u in 0 1 2 3 ; do mkdev pt$u c 96 $u ; done
for u in 0 1 2 3 ; do mkdev npt$u c 96 $[ $u + 128 ] ; done for u in 0 1 2 3 ; do mkdev npt$u c 96 $[ $u + 128 ] ; done
for u in 0 1 2 3 ; do mkdev pg$u c 97 $u ; done for u in 0 1 2 3 ; do mkdev pg$u c 97 $u ; done
# #
# end of mkd # end of mkd
With the device files and drivers in place, you can access PARIDE devices With the device files and drivers in place, you can access PARIDE devices
like any other Linux device. For example, to mount a CD-ROM in pcd0, use: like any other Linux device. For example, to mount a CD-ROM in pcd0, use::
mount /dev/pcd0 /cdrom mount /dev/pcd0 /cdrom
If you have a fresh Avatar Shark cartridge, and the drive is pda, you If you have a fresh Avatar Shark cartridge, and the drive is pda, you
might do something like: might do something like::
fdisk /dev/pda -- make a new partition table with fdisk /dev/pda -- make a new partition table with
partition 1 of type 83 partition 1 of type 83
@ -289,41 +303,46 @@ might do something like:
Devices like the Imation superdisk work in the same way, except that Devices like the Imation superdisk work in the same way, except that
they do not have a partition table. For example to make a 120MB they do not have a partition table. For example to make a 120MB
floppy that you could share with a DOS system: floppy that you could share with a DOS system::
mkdosfs /dev/pf0 mkdosfs /dev/pf0
mount /dev/pf0 /mnt mount /dev/pf0 /mnt
2.4 The pf driver 2.4 The pf driver
------------------
The pf driver is intended for use with parallel port ATAPI disk The pf driver is intended for use with parallel port ATAPI disk
devices. The most common devices in this category are PD drives devices. The most common devices in this category are PD drives
and LS-120 drives. Traditionally, media for these devices are not and LS-120 drives. Traditionally, media for these devices are not
partitioned. Consequently, the pf driver does not support partitioned partitioned. Consequently, the pf driver does not support partitioned
media. This may be changed in a future version of the driver. media. This may be changed in a future version of the driver.
2.5 Using the pt driver 2.5 Using the pt driver
------------------------
The pt driver for parallel port ATAPI tape drives is a minimal driver. The pt driver for parallel port ATAPI tape drives is a minimal driver.
It does not yet support many of the standard tape ioctl operations. It does not yet support many of the standard tape ioctl operations.
For best performance, a block size of 32KB should be used. You will For best performance, a block size of 32KB should be used. You will
probably want to set the parallel port delay to 0, if you can. probably want to set the parallel port delay to 0, if you can.
2.6 Using the pg driver 2.6 Using the pg driver
------------------------
The pg driver can be used in conjunction with the cdrecord program The pg driver can be used in conjunction with the cdrecord program
to create CD-ROMs. Please get cdrecord version 1.6.1 or later to create CD-ROMs. Please get cdrecord version 1.6.1 or later
from ftp://ftp.fokus.gmd.de/pub/unix/cdrecord/ . To record CD-R media from ftp://ftp.fokus.gmd.de/pub/unix/cdrecord/ . To record CD-R media
your parallel port should ideally be set to EPP mode, and the "port delay" your parallel port should ideally be set to EPP mode, and the "port delay"
should be set to 0. With those settings it is possible to record at 2x should be set to 0. With those settings it is possible to record at 2x
speed without any buffer underruns. If you cannot get the driver to work speed without any buffer underruns. If you cannot get the driver to work
in EPP mode, try to use "bidirectional" or "PS/2" mode and 1x speeds only. in EPP mode, try to use "bidirectional" or "PS/2" mode and 1x speeds only.
3. Troubleshooting 3. Troubleshooting
==================
3.1 Use EPP mode if you can 3.1 Use EPP mode if you can
----------------------------
The most common problems that people report with the PARIDE drivers The most common problems that people report with the PARIDE drivers
concern the parallel port CMOS settings. At this time, none of the concern the parallel port CMOS settings. At this time, none of the
@ -332,6 +351,7 @@ If you are able to do so, please set your parallel port into EPP mode
using your CMOS setup procedure. using your CMOS setup procedure.
3.2 Check the port delay 3.2 Check the port delay
-------------------------
Some parallel ports cannot reliably transfer data at full speed. To Some parallel ports cannot reliably transfer data at full speed. To
offset the errors, the PARIDE protocol modules introduce a "port offset the errors, the PARIDE protocol modules introduce a "port
@ -347,23 +367,25 @@ read the comments at the beginning of the driver source files in
linux/drivers/block/paride. linux/drivers/block/paride.
3.3 Some drives need a printer reset 3.3 Some drives need a printer reset
-------------------------------------
There appear to be a number of "noname" external drives on the market There appear to be a number of "noname" external drives on the market
that do not always power up correctly. We have noticed this with some that do not always power up correctly. We have noticed this with some
drives based on OnSpec and older Freecom adapters. In these rare cases, drives based on OnSpec and older Freecom adapters. In these rare cases,
the adapter can often be reinitialised by issuing a "printer reset" on the adapter can often be reinitialised by issuing a "printer reset" on
the parallel port. As the reset operation is potentially disruptive in the parallel port. As the reset operation is potentially disruptive in
multiple device environments, the PARIDE drivers will not do it multiple device environments, the PARIDE drivers will not do it
automatically. You can however, force a printer reset by doing: automatically. You can however, force a printer reset by doing::
insmod lp reset=1 insmod lp reset=1
rmmod lp rmmod lp
If you have one of these marginal cases, you should probably build If you have one of these marginal cases, you should probably build
your paride drivers as modules, and arrange to do the printer reset your paride drivers as modules, and arrange to do the printer reset
before loading the PARIDE drivers. before loading the PARIDE drivers.
3.4 Use the verbose option and dmesg if you need help 3.4 Use the verbose option and dmesg if you need help
------------------------------------------------------
While a lot of testing has gone into these drivers to make them work While a lot of testing has gone into these drivers to make them work
as smoothly as possible, problems will arise. If you do have problems, as smoothly as possible, problems will arise. If you do have problems,
@ -373,7 +395,7 @@ clues, then please make sure that only one drive is hooked to your system,
and that either (a) PARPORT is enabled or (b) no other device driver and that either (a) PARPORT is enabled or (b) no other device driver
is using your parallel port (check in /proc/ioports). Then, load the is using your parallel port (check in /proc/ioports). Then, load the
appropriate drivers (you can load several protocol modules if you want) appropriate drivers (you can load several protocol modules if you want)
as in: as in::
# insmod paride # insmod paride
# insmod epat # insmod epat
@ -394,12 +416,14 @@ by e-mail to grant@torque.net, or join the linux-parport mailing list
and post your report there. and post your report there.
3.5 For more information or help 3.5 For more information or help
---------------------------------
You can join the linux-parport mailing list by sending a mail message You can join the linux-parport mailing list by sending a mail message
to to:
linux-parport-request@torque.net linux-parport-request@torque.net
with the single word with the single word::
subscribe subscribe
@ -412,6 +436,4 @@ have in your mail headers, when sending mail to the list server.
You might also find some useful information on the linux-parport You might also find some useful information on the linux-parport
web pages (although they are not always up to date) at web pages (although they are not always up to date) at
http://web.archive.org/web/*/http://www.torque.net/parport/ http://web.archive.org/web/%2E/http://www.torque.net/parport/

55
Documentation/blockdev/ramdisk.txt → Documentation/blockdev/ramdisk.rst
View File

@ -1,7 +1,8 @@
==========================================
Using the RAM disk block device with Linux Using the RAM disk block device with Linux
------------------------------------------ ==========================================
Contents: .. Contents:
1) Overview 1) Overview
2) Kernel Command Line Parameters 2) Kernel Command Line Parameters
@ -42,7 +43,7 @@ rescue floppy disk.
2a) Kernel Command Line Parameters 2a) Kernel Command Line Parameters
ramdisk_size=N ramdisk_size=N
============== Size of the ramdisk.
This parameter tells the RAM disk driver to set up RAM disks of N k size. The This parameter tells the RAM disk driver to set up RAM disks of N k size. The
default is 4096 (4 MB). default is 4096 (4 MB).
@ -50,16 +51,13 @@ default is 4096 (4 MB).
2b) Module parameters 2b) Module parameters
rd_nr rd_nr
===== /dev/ramX devices created.
/dev/ramX devices created.
max_part max_part
======== Maximum partition number.
Maximum partition number.
rd_size rd_size
======= See ramdisk_size.
See ramdisk_size.
3) Using "rdev -r" 3) Using "rdev -r"
------------------ ------------------
@ -71,11 +69,11 @@ to 2 MB (2^11) of where to find the RAM disk (this used to be the size). Bit
prompt/wait sequence is to be given before trying to read the RAM disk. Since prompt/wait sequence is to be given before trying to read the RAM disk. Since
the RAM disk dynamically grows as data is being written into it, a size field the RAM disk dynamically grows as data is being written into it, a size field
is not required. Bits 11 to 13 are not currently used and may as well be zero. is not required. Bits 11 to 13 are not currently used and may as well be zero.
These numbers are no magical secrets, as seen below: These numbers are no magical secrets, as seen below::
./arch/x86/kernel/setup.c:#define RAMDISK_IMAGE_START_MASK 0x07FF ./arch/x86/kernel/setup.c:#define RAMDISK_IMAGE_START_MASK 0x07FF
./arch/x86/kernel/setup.c:#define RAMDISK_PROMPT_FLAG 0x8000 ./arch/x86/kernel/setup.c:#define RAMDISK_PROMPT_FLAG 0x8000
./arch/x86/kernel/setup.c:#define RAMDISK_LOAD_FLAG 0x4000 ./arch/x86/kernel/setup.c:#define RAMDISK_LOAD_FLAG 0x4000
Consider a typical two floppy disk setup, where you will have the Consider a typical two floppy disk setup, where you will have the
kernel on disk one, and have already put a RAM disk image onto disk #2. kernel on disk one, and have already put a RAM disk image onto disk #2.
@ -92,20 +90,23 @@ sequence so that you have a chance to switch floppy disks.
The command line equivalent is: "prompt_ramdisk=1" The command line equivalent is: "prompt_ramdisk=1"
Putting that together gives 2^15 + 2^14 + 0 = 49152 for an rdev word. Putting that together gives 2^15 + 2^14 + 0 = 49152 for an rdev word.
So to create disk one of the set, you would do: So to create disk one of the set, you would do::
/usr/src/linux# cat arch/x86/boot/zImage > /dev/fd0 /usr/src/linux# cat arch/x86/boot/zImage > /dev/fd0
/usr/src/linux# rdev /dev/fd0 /dev/fd0 /usr/src/linux# rdev /dev/fd0 /dev/fd0
/usr/src/linux# rdev -r /dev/fd0 49152 /usr/src/linux# rdev -r /dev/fd0 49152
If you make a boot disk that has LILO, then for the above, you would use: If you make a boot disk that has LILO, then for the above, you would use::
append = "ramdisk_start=0 load_ramdisk=1 prompt_ramdisk=1" append = "ramdisk_start=0 load_ramdisk=1 prompt_ramdisk=1"
Since the default start = 0 and the default prompt = 1, you could use:
Since the default start = 0 and the default prompt = 1, you could use::
append = "load_ramdisk=1" append = "load_ramdisk=1"
4) An Example of Creating a Compressed RAM Disk 4) An Example of Creating a Compressed RAM Disk
---------------------------------------------- -----------------------------------------------
To create a RAM disk image, you will need a spare block device to To create a RAM disk image, you will need a spare block device to
construct it on. This can be the RAM disk device itself, or an construct it on. This can be the RAM disk device itself, or an
@ -120,11 +121,11 @@ a) Decide on the RAM disk size that you want. Say 2 MB for this example.
Create it by writing to the RAM disk device. (This step is not currently Create it by writing to the RAM disk device. (This step is not currently
required, but may be in the future.) It is wise to zero out the required, but may be in the future.) It is wise to zero out the
area (esp. for disks) so that maximal compression is achieved for area (esp. for disks) so that maximal compression is achieved for
the unused blocks of the image that you are about to create. the unused blocks of the image that you are about to create::
dd if=/dev/zero of=/dev/ram0 bs=1k count=2048 dd if=/dev/zero of=/dev/ram0 bs=1k count=2048
b) Make a filesystem on it. Say ext2fs for this example. b) Make a filesystem on it. Say ext2fs for this example::
mke2fs -vm0 /dev/ram0 2048 mke2fs -vm0 /dev/ram0 2048
@ -133,11 +134,11 @@ c) Mount it, copy the files you want to it (eg: /etc/* /dev/* ...)
d) Compress the contents of the RAM disk. The level of compression d) Compress the contents of the RAM disk. The level of compression
will be approximately 50% of the space used by the files. Unused will be approximately 50% of the space used by the files. Unused
space on the RAM disk will compress to almost nothing. space on the RAM disk will compress to almost nothing::
dd if=/dev/ram0 bs=1k count=2048 | gzip -v9 > /tmp/ram_image.gz dd if=/dev/ram0 bs=1k count=2048 | gzip -v9 > /tmp/ram_image.gz
e) Put the kernel onto the floppy e) Put the kernel onto the floppy::
dd if=zImage of=/dev/fd0 bs=1k dd if=zImage of=/dev/fd0 bs=1k
@ -146,13 +147,13 @@ f) Put the RAM disk image onto the floppy, after the kernel. Use an offset
(possibly larger) kernel onto the same floppy later without overlapping (possibly larger) kernel onto the same floppy later without overlapping
the RAM disk image. An offset of 400 kB for kernels about 350 kB in the RAM disk image. An offset of 400 kB for kernels about 350 kB in
size would be reasonable. Make sure offset+size of ram_image.gz is size would be reasonable. Make sure offset+size of ram_image.gz is
not larger than the total space on your floppy (usually 1440 kB). not larger than the total space on your floppy (usually 1440 kB)::
dd if=/tmp/ram_image.gz of=/dev/fd0 bs=1k seek=400 dd if=/tmp/ram_image.gz of=/dev/fd0 bs=1k seek=400
g) Use "rdev" to set the boot device, RAM disk offset, prompt flag, etc. g) Use "rdev" to set the boot device, RAM disk offset, prompt flag, etc.
For prompt_ramdisk=1, load_ramdisk=1, ramdisk_start=400, one would For prompt_ramdisk=1, load_ramdisk=1, ramdisk_start=400, one would
have 2^15 + 2^14 + 400 = 49552. have 2^15 + 2^14 + 400 = 49552::
rdev /dev/fd0 /dev/fd0 rdev /dev/fd0 /dev/fd0
rdev -r /dev/fd0 49552 rdev -r /dev/fd0 49552
@ -160,15 +161,17 @@ g) Use "rdev" to set the boot device, RAM disk offset, prompt flag, etc.
That is it. You now have your boot/root compressed RAM disk floppy. Some That is it. You now have your boot/root compressed RAM disk floppy. Some
users may wish to combine steps (d) and (f) by using a pipe. users may wish to combine steps (d) and (f) by using a pipe.
--------------------------------------------------------------------------
Paul Gortmaker 12/95 Paul Gortmaker 12/95
Changelog: Changelog:
---------- ----------
10-22-04 : Updated to reflect changes in command line options, remove 10-22-04 :
Updated to reflect changes in command line options, remove
obsolete references, general cleanup. obsolete references, general cleanup.
James Nelson (james4765@gmail.com) James Nelson (james4765@gmail.com)
12-95 : Original Document 12-95 :
Original Document

195
Documentation/blockdev/zram.txt → Documentation/blockdev/zram.rst
View File

@ -1,7 +1,9 @@
========================================
zram: Compressed RAM based block devices zram: Compressed RAM based block devices
---------------------------------------- ========================================
* Introduction Introduction
============
The zram module creates RAM based block devices named /dev/zram<id> The zram module creates RAM based block devices named /dev/zram<id>
(<id> = 0, 1, ...). Pages written to these disks are compressed and stored (<id> = 0, 1, ...). Pages written to these disks are compressed and stored
@ -12,9 +14,11 @@ use as swap disks, various caches under /var and maybe many more :)
Statistics for individual zram devices are exported through sysfs nodes at Statistics for individual zram devices are exported through sysfs nodes at
/sys/block/zram<id>/ /sys/block/zram<id>/
* Usage Usage
=====
There are several ways to configure and manage zram device(-s): There are several ways to configure and manage zram device(-s):
a) using zram and zram_control sysfs attributes a) using zram and zram_control sysfs attributes
b) using zramctl utility, provided by util-linux (util-linux@vger.kernel.org). b) using zramctl utility, provided by util-linux (util-linux@vger.kernel.org).
@ -22,7 +26,7 @@ In this document we will describe only 'manual' zram configuration steps,
IOW, zram and zram_control sysfs attributes. IOW, zram and zram_control sysfs attributes.
In order to get a better idea about zramctl please consult util-linux In order to get a better idea about zramctl please consult util-linux
documentation, zramctl man-page or `zramctl --help'. Please be informed documentation, zramctl man-page or `zramctl --help`. Please be informed
that zram maintainers do not develop/maintain util-linux or zramctl, should that zram maintainers do not develop/maintain util-linux or zramctl, should
you have any questions please contact util-linux@vger.kernel.org you have any questions please contact util-linux@vger.kernel.org
@ -30,19 +34,23 @@ Following shows a typical sequence of steps for using zram.
WARNING WARNING
======= =======
For the sake of simplicity we skip error checking parts in most of the For the sake of simplicity we skip error checking parts in most of the
examples below. However, it is your sole responsibility to handle errors. examples below. However, it is your sole responsibility to handle errors.
zram sysfs attributes always return negative values in case of errors. zram sysfs attributes always return negative values in case of errors.
The list of possible return codes: The list of possible return codes:
-EBUSY -- an attempt to modify an attribute that cannot be changed once
the device has been initialised. Please reset device first; ======== =============================================================
-ENOMEM -- zram was not able to allocate enough memory to fulfil your -EBUSY an attempt to modify an attribute that cannot be changed once
needs; the device has been initialised. Please reset device first;
-EINVAL -- invalid input has been provided. -ENOMEM zram was not able to allocate enough memory to fulfil your
needs;
-EINVAL invalid input has been provided.
======== =============================================================
If you use 'echo', the returned value that is changed by 'echo' utility, If you use 'echo', the returned value that is changed by 'echo' utility,
and, in general case, something like: and, in general case, something like::
echo 3 > /sys/block/zram0/max_comp_streams echo 3 > /sys/block/zram0/max_comp_streams
if [ $? -ne 0 ]; if [ $? -ne 0 ];
@ -51,7 +59,11 @@ and, in general case, something like:
should suffice. should suffice.
1) Load Module: 1) Load Module
==============
::
modprobe zram num_devices=4 modprobe zram num_devices=4
This creates 4 devices: /dev/zram{0,1,2,3} This creates 4 devices: /dev/zram{0,1,2,3}
@ -59,6 +71,8 @@ num_devices parameter is optional and tells zram how many devices should be
pre-created. Default: 1. pre-created. Default: 1.
2) Set max number of compression streams 2) Set max number of compression streams
========================================
Regardless the value passed to this attribute, ZRAM will always Regardless the value passed to this attribute, ZRAM will always
allocate multiple compression streams - one per online CPUs - thus allocate multiple compression streams - one per online CPUs - thus
allowing several concurrent compression operations. The number of allowing several concurrent compression operations. The number of
@ -66,16 +80,20 @@ allocated compression streams goes down when some of the CPUs
become offline. There is no single-compression-stream mode anymore, become offline. There is no single-compression-stream mode anymore,
unless you are running a UP system or has only 1 CPU online. unless you are running a UP system or has only 1 CPU online.
To find out how many streams are currently available: To find out how many streams are currently available::
cat /sys/block/zram0/max_comp_streams cat /sys/block/zram0/max_comp_streams
3) Select compression algorithm 3) Select compression algorithm
===============================
Using comp_algorithm device attribute one can see available and Using comp_algorithm device attribute one can see available and
currently selected (shown in square brackets) compression algorithms, currently selected (shown in square brackets) compression algorithms,
change selected compression algorithm (once the device is initialised change selected compression algorithm (once the device is initialised
there is no way to change compression algorithm). there is no way to change compression algorithm).
Examples: Examples::
#show supported compression algorithms #show supported compression algorithms
cat /sys/block/zram0/comp_algorithm cat /sys/block/zram0/comp_algorithm
lzo [lz4] lzo [lz4]
@ -83,20 +101,23 @@ Examples:
#select lzo compression algorithm #select lzo compression algorithm
echo lzo > /sys/block/zram0/comp_algorithm echo lzo > /sys/block/zram0/comp_algorithm
For the time being, the `comp_algorithm' content does not necessarily For the time being, the `comp_algorithm` content does not necessarily
show every compression algorithm supported by the kernel. We keep this show every compression algorithm supported by the kernel. We keep this
list primarily to simplify device configuration and one can configure list primarily to simplify device configuration and one can configure
a new device with a compression algorithm that is not listed in a new device with a compression algorithm that is not listed in
`comp_algorithm'. The thing is that, internally, ZRAM uses Crypto API `comp_algorithm`. The thing is that, internally, ZRAM uses Crypto API
and, if some of the algorithms were built as modules, it's impossible and, if some of the algorithms were built as modules, it's impossible
to list all of them using, for instance, /proc/crypto or any other to list all of them using, for instance, /proc/crypto or any other
method. This, however, has an advantage of permitting the usage of method. This, however, has an advantage of permitting the usage of
custom crypto compression modules (implementing S/W or H/W compression). custom crypto compression modules (implementing S/W or H/W compression).
4) Set Disksize 4) Set Disksize
===============
Set disk size by writing the value to sysfs node 'disksize'. Set disk size by writing the value to sysfs node 'disksize'.
The value can be either in bytes or you can use mem suffixes. The value can be either in bytes or you can use mem suffixes.
Examples: Examples::
# Initialize /dev/zram0 with 50MB disksize # Initialize /dev/zram0 with 50MB disksize
echo $((50*1024*1024)) > /sys/block/zram0/disksize echo $((50*1024*1024)) > /sys/block/zram0/disksize
@ -111,10 +132,13 @@ since we expect a 2:1 compression ratio. Note that zram uses about 0.1% of the
size of the disk when not in use so a huge zram is wasteful. size of the disk when not in use so a huge zram is wasteful.
5) Set memory limit: Optional 5) Set memory limit: Optional
=============================
Set memory limit by writing the value to sysfs node 'mem_limit'. Set memory limit by writing the value to sysfs node 'mem_limit'.
The value can be either in bytes or you can use mem suffixes. The value can be either in bytes or you can use mem suffixes.
In addition, you could change the value in runtime. In addition, you could change the value in runtime.
Examples: Examples::
# limit /dev/zram0 with 50MB memory # limit /dev/zram0 with 50MB memory
echo $((50*1024*1024)) > /sys/block/zram0/mem_limit echo $((50*1024*1024)) > /sys/block/zram0/mem_limit
@ -126,7 +150,11 @@ Examples:
# To disable memory limit # To disable memory limit
echo 0 > /sys/block/zram0/mem_limit echo 0 > /sys/block/zram0/mem_limit
6) Activate: 6) Activate
===========
::
mkswap /dev/zram0 mkswap /dev/zram0
swapon /dev/zram0 swapon /dev/zram0
@ -134,6 +162,7 @@ Examples:
mount /dev/zram1 /tmp mount /dev/zram1 /tmp
7) Add/remove zram devices 7) Add/remove zram devices
==========================
zram provides a control interface, which enables dynamic (on-demand) device zram provides a control interface, which enables dynamic (on-demand) device
addition and removal. addition and removal.
@ -142,37 +171,44 @@ In order to add a new /dev/zramX device, perform read operation on hot_add
attribute. This will return either new device's device id (meaning that you attribute. This will return either new device's device id (meaning that you
can use /dev/zram<id>) or error code. can use /dev/zram<id>) or error code.
Example: Example::
cat /sys/class/zram-control/hot_add cat /sys/class/zram-control/hot_add
1 1
To remove the existing /dev/zramX device (where X is a device id) To remove the existing /dev/zramX device (where X is a device id)
execute execute::
echo X > /sys/class/zram-control/hot_remove echo X > /sys/class/zram-control/hot_remove
8) Stats: 8) Stats
========
Per-device statistics are exported as various nodes under /sys/block/zram<id>/ Per-device statistics are exported as various nodes under /sys/block/zram<id>/
A brief description of exported device attributes. For more details please A brief description of exported device attributes. For more details please
read Documentation/ABI/testing/sysfs-block-zram. read Documentation/ABI/testing/sysfs-block-zram.
====================== ====== ===============================================
Name access description Name access description
---- ------ ----------- ====================== ====== ===============================================
disksize RW show and set the device's disk size disksize RW show and set the device's disk size
initstate RO shows the initialization state of the device initstate RO shows the initialization state of the device
reset WO trigger device reset reset WO trigger device reset
mem_used_max WO reset the `mem_used_max' counter (see later) mem_used_max WO reset the `mem_used_max` counter (see later)
mem_limit WO specifies the maximum amount of memory ZRAM can use mem_limit WO specifies the maximum amount of memory ZRAM can
to store the compressed data use to store the compressed data
writeback_limit WO specifies the maximum amount of write IO zram can writeback_limit WO specifies the maximum amount of write IO zram
write out to backing device as 4KB unit can write out to backing device as 4KB unit
writeback_limit_enable RW show and set writeback_limit feature writeback_limit_enable RW show and set writeback_limit feature
max_comp_streams RW the number of possible concurrent compress operations max_comp_streams RW the number of possible concurrent compress
operations
comp_algorithm RW show and change the compression algorithm comp_algorithm RW show and change the compression algorithm
compact WO trigger memory compaction compact WO trigger memory compaction
debug_stat RO this file is used for zram debugging purposes debug_stat RO this file is used for zram debugging purposes
backing_dev RW set up backend storage for zram to write out backing_dev RW set up backend storage for zram to write out
idle WO mark allocated slot as idle idle WO mark allocated slot as idle
====================== ====== ===============================================
User space is advised to use the following files to read the device statistics. User space is advised to use the following files to read the device statistics.
@ -188,23 +224,31 @@ The stat file represents device's I/O statistics not accounted by block
layer and, thus, not available in zram<id>/stat file. It consists of a layer and, thus, not available in zram<id>/stat file. It consists of a
single line of text and contains the following stats separated by single line of text and contains the following stats separated by
whitespace: whitespace:
failed_reads the number of failed reads
failed_writes the number of failed writes ============= =============================================================
invalid_io the number of non-page-size-aligned I/O requests failed_reads The number of failed reads
failed_writes The number of failed writes
invalid_io The number of non-page-size-aligned I/O requests
notify_free Depending on device usage scenario it may account notify_free Depending on device usage scenario it may account
a) the number of pages freed because of swap slot free a) the number of pages freed because of swap slot free
notifications or b) the number of pages freed because of notifications
REQ_OP_DISCARD requests sent by bio. The former ones are b) the number of pages freed because of
sent to a swap block device when a swap slot is freed, REQ_OP_DISCARD requests sent by bio. The former ones are
which implies that this disk is being used as a swap disk. sent to a swap block device when a swap slot is freed,
which implies that this disk is being used as a swap disk.
The latter ones are sent by filesystem mounted with The latter ones are sent by filesystem mounted with
discard option, whenever some data blocks are getting discard option, whenever some data blocks are getting
discarded. discarded.
============= =============================================================
File /sys/block/zram<id>/mm_stat File /sys/block/zram<id>/mm_stat
The stat file represents device's mm statistics. It consists of a single The stat file represents device's mm statistics. It consists of a single
line of text and contains the following stats separated by whitespace: line of text and contains the following stats separated by whitespace:
================ =============================================================
orig_data_size uncompressed size of data stored in this disk. orig_data_size uncompressed size of data stored in this disk.
This excludes same-element-filled pages (same_pages) since This excludes same-element-filled pages (same_pages) since
no memory is allocated for them. no memory is allocated for them.
@ -223,58 +267,71 @@ line of text and contains the following stats separated by whitespace:
No memory is allocated for such pages. No memory is allocated for such pages.
pages_compacted the number of pages freed during compaction pages_compacted the number of pages freed during compaction
huge_pages the number of incompressible pages huge_pages the number of incompressible pages
================ =============================================================
File /sys/block/zram<id>/bd_stat File /sys/block/zram<id>/bd_stat
The stat file represents device's backing device statistics. It consists of The stat file represents device's backing device statistics. It consists of
a single line of text and contains the following stats separated by whitespace: a single line of text and contains the following stats separated by whitespace:
============== =============================================================
bd_count size of data written in backing device. bd_count size of data written in backing device.
Unit: 4K bytes Unit: 4K bytes
bd_reads the number of reads from backing device bd_reads the number of reads from backing device
Unit: 4K bytes Unit: 4K bytes
bd_writes the number of writes to backing device bd_writes the number of writes to backing device
Unit: 4K bytes Unit: 4K bytes
============== =============================================================
9) Deactivate
=============
::
9) Deactivate:
swapoff /dev/zram0 swapoff /dev/zram0
umount /dev/zram1 umount /dev/zram1
10) Reset: 10) Reset
Write any positive value to 'reset' sysfs node =========
echo 1 > /sys/block/zram0/reset
echo 1 > /sys/block/zram1/reset Write any positive value to 'reset' sysfs node::
echo 1 > /sys/block/zram0/reset
echo 1 > /sys/block/zram1/reset
This frees all the memory allocated for the given device and This frees all the memory allocated for the given device and
resets the disksize to zero. You must set the disksize again resets the disksize to zero. You must set the disksize again
before reusing the device. before reusing the device.
* Optional Feature Optional Feature
================
= writeback writeback
---------
With CONFIG_ZRAM_WRITEBACK, zram can write idle/incompressible page With CONFIG_ZRAM_WRITEBACK, zram can write idle/incompressible page
to backing storage rather than keeping it in memory. to backing storage rather than keeping it in memory.
To use the feature, admin should set up backing device via To use the feature, admin should set up backing device via::
"echo /dev/sda5 > /sys/block/zramX/backing_dev" echo /dev/sda5 > /sys/block/zramX/backing_dev
before disksize setting. It supports only partition at this moment. before disksize setting. It supports only partition at this moment.
If admin want to use incompressible page writeback, they could do via If admin want to use incompressible page writeback, they could do via::
"echo huge > /sys/block/zramX/write" echo huge > /sys/block/zramX/write
To use idle page writeback, first, user need to declare zram pages To use idle page writeback, first, user need to declare zram pages
as idle. as idle::
"echo all > /sys/block/zramX/idle" echo all > /sys/block/zramX/idle
From now on, any pages on zram are idle pages. The idle mark From now on, any pages on zram are idle pages. The idle mark
will be removed until someone request access of the block. will be removed until someone request access of the block.
IOW, unless there is access request, those pages are still idle pages. IOW, unless there is access request, those pages are still idle pages.
Admin can request writeback of those idle pages at right timing via Admin can request writeback of those idle pages at right timing via::
"echo idle > /sys/block/zramX/writeback" echo idle > /sys/block/zramX/writeback
With the command, zram writeback idle pages from memory to the storage. With the command, zram writeback idle pages from memory to the storage.
@ -285,7 +342,7 @@ to guarantee storage health for entire product life.
To overcome the concern, zram supports "writeback_limit" feature. To overcome the concern, zram supports "writeback_limit" feature.
The "writeback_limit_enable"'s default value is 0 so that it doesn't limit The "writeback_limit_enable"'s default value is 0 so that it doesn't limit
any writeback. IOW, if admin want to apply writeback budget, he should any writeback. IOW, if admin want to apply writeback budget, he should
enable writeback_limit_enable via enable writeback_limit_enable via::
$ echo 1 > /sys/block/zramX/writeback_limit_enable $ echo 1 > /sys/block/zramX/writeback_limit_enable
@ -296,7 +353,7 @@ until admin set the budget via /sys/block/zramX/writeback_limit.
assigned via /sys/block/zramX/writeback_limit is meaninless.) assigned via /sys/block/zramX/writeback_limit is meaninless.)
If admin want to limit writeback as per-day 400M, he could do it If admin want to limit writeback as per-day 400M, he could do it
like below. like below::
$ MB_SHIFT=20 $ MB_SHIFT=20
$ 4K_SHIFT=12 $ 4K_SHIFT=12
@ -305,16 +362,16 @@ like below.
$ echo 1 > /sys/block/zram0/writeback_limit_enable $ echo 1 > /sys/block/zram0/writeback_limit_enable
If admin want to allow further write again once the bugdet is exausted, If admin want to allow further write again once the bugdet is exausted,
he could do it like below he could do it like below::
$ echo $((400<<MB_SHIFT>>4K_SHIFT)) > \ $ echo $((400<<MB_SHIFT>>4K_SHIFT)) > \
/sys/block/zram0/writeback_limit /sys/block/zram0/writeback_limit
If admin want to see remaining writeback budget since he set, If admin want to see remaining writeback budget since he set::
$ cat /sys/block/zramX/writeback_limit $ cat /sys/block/zramX/writeback_limit
If admin want to disable writeback limit, he could do If admin want to disable writeback limit, he could do::
$ echo 0 > /sys/block/zramX/writeback_limit_enable $ echo 0 > /sys/block/zramX/writeback_limit_enable
@ -326,25 +383,35 @@ budget in next setting is user's job.
If admin want to measure writeback count in a certain period, he could If admin want to measure writeback count in a certain period, he could
know it via /sys/block/zram0/bd_stat's 3rd column. know it via /sys/block/zram0/bd_stat's 3rd column.
= memory tracking memory tracking
===============
With CONFIG_ZRAM_MEMORY_TRACKING, user can know information of the With CONFIG_ZRAM_MEMORY_TRACKING, user can know information of the
zram block. It could be useful to catch cold or incompressible zram block. It could be useful to catch cold or incompressible
pages of the process with*pagemap. pages of the process with*pagemap.
If you enable the feature, you could see block state via If you enable the feature, you could see block state via
/sys/kernel/debug/zram/zram0/block_state". The output is as follows, /sys/kernel/debug/zram/zram0/block_state". The output is as follows::
300 75.033841 .wh. 300 75.033841 .wh.
301 63.806904 s... 301 63.806904 s...
302 63.806919 ..hi 302 63.806919 ..hi
First column is zram's block index. First column
Second column is access time since the system was booted zram's block index.
Third column is state of the block. Second column
(s: same page access time since the system was booted
w: written page to backing store Third column
h: huge page state of the block:
i: idle page)
s:
same page
w:
written page to backing store
h:
huge page
i:
idle page
First line of above example says 300th block is accessed at 75.033841sec First line of above example says 300th block is accessed at 75.033841sec
and the block's state is huge so it is written back to the backing and the block's state is huge so it is written back to the backing

8
MAINTAINERS
View File

@ -11076,7 +11076,7 @@ M: Josef Bacik <josef@toxicpanda.com>
S: Maintained S: Maintained
L: linux-block@vger.kernel.org L: linux-block@vger.kernel.org
L: nbd@other.debian.org L: nbd@other.debian.org
F: Documentation/blockdev/nbd.txt F: Documentation/blockdev/nbd.rst
F: drivers/block/nbd.c F: drivers/block/nbd.c
F: include/trace/events/nbd.h F: include/trace/events/nbd.h
F: include/uapi/linux/nbd.h F: include/uapi/linux/nbd.h
@ -12086,7 +12086,7 @@ PARIDE DRIVERS FOR PARALLEL PORT IDE DEVICES
M: Tim Waugh <tim@cyberelk.net> M: Tim Waugh <tim@cyberelk.net>
L: linux-parport@lists.infradead.org (subscribers-only) L: linux-parport@lists.infradead.org (subscribers-only)
S: Maintained S: Maintained
F: Documentation/blockdev/paride.txt F: Documentation/blockdev/paride.rst
F: drivers/block/paride/ F: drivers/block/paride/
PARISC ARCHITECTURE PARISC ARCHITECTURE
@ -13367,7 +13367,7 @@ F: drivers/net/wireless/ralink/rt2x00/
RAMDISK RAM BLOCK DEVICE DRIVER RAMDISK RAM BLOCK DEVICE DRIVER
M: Jens Axboe <axboe@kernel.dk> M: Jens Axboe <axboe@kernel.dk>
S: Maintained S: Maintained
F: Documentation/blockdev/ramdisk.txt F: Documentation/blockdev/ramdisk.rst
F: drivers/block/brd.c F: drivers/block/brd.c
RANCHU VIRTUAL BOARD FOR MIPS RANCHU VIRTUAL BOARD FOR MIPS
@ -17723,7 +17723,7 @@ R: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
L: linux-kernel@vger.kernel.org L: linux-kernel@vger.kernel.org
S: Maintained S: Maintained
F: drivers/block/zram/ F: drivers/block/zram/
F: Documentation/blockdev/zram.txt F: Documentation/blockdev/zram.rst
ZS DECSTATION Z85C30 SERIAL DRIVER ZS DECSTATION Z85C30 SERIAL DRIVER
M: "Maciej W. Rozycki" <macro@linux-mips.org> M: "Maciej W. Rozycki" <macro@linux-mips.org>

8
drivers/block/Kconfig
View File

@ -31,7 +31,7 @@ config BLK_DEV_FD
If you want to use the floppy disk drive(s) of your PC under Linux, If you want to use the floppy disk drive(s) of your PC under Linux,
say Y. Information about this driver, especially important for IBM say Y. Information about this driver, especially important for IBM
Thinkpad users, is contained in Thinkpad users, is contained in
<file:Documentation/blockdev/floppy.txt>. <file:Documentation/blockdev/floppy.rst>.
That file also contains the location of the Floppy driver FAQ as That file also contains the location of the Floppy driver FAQ as
well as location of the fdutils package used to configure additional well as location of the fdutils package used to configure additional
parameters of the driver at run time. parameters of the driver at run time.
@ -96,7 +96,7 @@ config PARIDE
your computer's parallel port. Most of them are actually IDE devices your computer's parallel port. Most of them are actually IDE devices
using a parallel port IDE adapter. This option enables the PARIDE using a parallel port IDE adapter. This option enables the PARIDE
subsystem which contains drivers for many of these external drives. subsystem which contains drivers for many of these external drives.
Read <file:Documentation/blockdev/paride.txt> for more information. Read <file:Documentation/blockdev/paride.rst> for more information.
If you have said Y to the "Parallel-port support" configuration If you have said Y to the "Parallel-port support" configuration
option, you may share a single port between your printer and other option, you may share a single port between your printer and other
@ -261,7 +261,7 @@ config BLK_DEV_NBD
userland (making server and client physically the same computer, userland (making server and client physically the same computer,
communicating using the loopback network device). communicating using the loopback network device).
Read <file:Documentation/blockdev/nbd.txt> for more information, Read <file:Documentation/blockdev/nbd.rst> for more information,
especially about where to find the server code, which runs in user especially about where to find the server code, which runs in user
space and does not need special kernel support. space and does not need special kernel support.
@ -303,7 +303,7 @@ config BLK_DEV_RAM
during the initial install of Linux. during the initial install of Linux.
Note that the kernel command line option "ramdisk=XX" is now obsolete. Note that the kernel command line option "ramdisk=XX" is now obsolete.
For details, read <file:Documentation/blockdev/ramdisk.txt>. For details, read <file:Documentation/blockdev/ramdisk.rst>.
To compile this driver as a module, choose M here: the To compile this driver as a module, choose M here: the
module will be called brd. An alias "rd" has been defined module will be called brd. An alias "rd" has been defined

2
drivers/block/floppy.c
View File

@ -4424,7 +4424,7 @@ static int __init floppy_setup(char *str)
pr_cont("\n"); pr_cont("\n");
} else } else
DPRINT("botched floppy option\n"); DPRINT("botched floppy option\n");
DPRINT("Read Documentation/blockdev/floppy.txt\n"); DPRINT("Read Documentation/blockdev/floppy.rst\n");
return 0; return 0;
} }

6
drivers/block/zram/Kconfig
View File

@ -12,7 +12,7 @@ config ZRAM
It has several use cases, for example: /tmp storage, use as swap It has several use cases, for example: /tmp storage, use as swap
disks and maybe many more. disks and maybe many more.
See Documentation/blockdev/zram.txt for more information. See Documentation/blockdev/zram.rst for more information.
config ZRAM_WRITEBACK config ZRAM_WRITEBACK
bool "Write back incompressible or idle page to backing device" bool "Write back incompressible or idle page to backing device"
@ -26,7 +26,7 @@ config ZRAM_WRITEBACK
With /sys/block/zramX/{idle,writeback}, application could ask With /sys/block/zramX/{idle,writeback}, application could ask
idle page's writeback to the backing device to save in memory. idle page's writeback to the backing device to save in memory.
See Documentation/blockdev/zram.txt for more information. See Documentation/blockdev/zram.rst for more information.
config ZRAM_MEMORY_TRACKING config ZRAM_MEMORY_TRACKING
bool "Track zRam block status" bool "Track zRam block status"
@ -36,4 +36,4 @@ config ZRAM_MEMORY_TRACKING
of zRAM. Admin could see the information via of zRAM. Admin could see the information via
/sys/kernel/debug/zram/zramX/block_state. /sys/kernel/debug/zram/zramX/block_state.
See Documentation/blockdev/zram.txt for more information. See Documentation/blockdev/zram.rst for more information.

2
tools/testing/selftests/zram/README
View File

@ -37,4 +37,4 @@ Commands required for testing:
- mkfs/ mkfs.ext4 - mkfs/ mkfs.ext4
For more information please refer: For more information please refer:
kernel-source-tree/Documentation/blockdev/zram.txt kernel-source-tree/Documentation/blockdev/zram.rst