diff options
author | Mauro Carvalho Chehab <mchehab+samsung@kernel.org> | 2019-04-18 17:29:24 -0300 |
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committer | Mauro Carvalho Chehab <mchehab+samsung@kernel.org> | 2019-07-15 09:20:26 -0300 |
commit | 39443104c7d3f2b05a4a330fbcef6da68f80d60b (patch) | |
tree | 4405b2a60e9fa358522e4b90f564b135ff638c02 /Documentation/blockdev | |
parent | e0ae154404c33477473244f286b1193364144289 (diff) | |
download | linux-39443104c7d3f2b05a4a330fbcef6da68f80d60b.tar.bz2 |
docs: blockdev: convert to ReST
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>
Diffstat (limited to 'Documentation/blockdev')
-rw-r--r-- | Documentation/blockdev/drbd/data-structure-v9.rst (renamed from Documentation/blockdev/drbd/data-structure-v9.txt) | 6 | ||||
-rw-r--r-- | Documentation/blockdev/drbd/figures.rst | 28 | ||||
-rw-r--r-- | Documentation/blockdev/drbd/index.rst (renamed from Documentation/blockdev/drbd/README.txt) | 15 | ||||
-rw-r--r-- | Documentation/blockdev/floppy.rst (renamed from Documentation/blockdev/floppy.txt) | 88 | ||||
-rw-r--r-- | Documentation/blockdev/index.rst | 16 | ||||
-rw-r--r-- | Documentation/blockdev/nbd.rst (renamed from Documentation/blockdev/nbd.txt) | 2 | ||||
-rw-r--r-- | Documentation/blockdev/paride.rst (renamed from Documentation/blockdev/paride.txt) | 196 | ||||
-rw-r--r-- | Documentation/blockdev/ramdisk.rst (renamed from Documentation/blockdev/ramdisk.txt) | 55 | ||||
-rw-r--r-- | Documentation/blockdev/zram.rst (renamed from Documentation/blockdev/zram.txt) | 195 |
9 files changed, 377 insertions, 224 deletions
diff --git a/Documentation/blockdev/drbd/data-structure-v9.txt b/Documentation/blockdev/drbd/data-structure-v9.rst index 1e52a0e32624..66036b901644 100644 --- a/Documentation/blockdev/drbd/data-structure-v9.txt +++ b/Documentation/blockdev/drbd/data-structure-v9.rst @@ -1,3 +1,7 @@ +================================ +kernel data structure for DRBD-9 +================================ + This describes the in kernel data structure for DRBD-9. Starting with 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 drbd_peer_device object sits at each intersection between a drbd_device and a -drbd_connection: +drbd_connection:: /--------------+---------------+.....+---------------\ | resource | device | | device | diff --git a/Documentation/blockdev/drbd/figures.rst b/Documentation/blockdev/drbd/figures.rst new file mode 100644 index 000000000000..3e3fd4b8a478 --- /dev/null +++ b/Documentation/blockdev/drbd/figures.rst @@ -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 diff --git a/Documentation/blockdev/drbd/README.txt b/Documentation/blockdev/drbd/index.rst index 627b0a1bf35e..68ecd5c113e9 100644 --- a/Documentation/blockdev/drbd/README.txt +++ b/Documentation/blockdev/drbd/index.rst @@ -1,4 +1,9 @@ +========================================== +Distributed Replicated Block Device - DRBD +========================================== + Description +=========== DRBD is a shared-nothing, synchronously replicated block device. It 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. -The here included files are intended to help understand the implementation - -DRBD-8.3-data-packets.svg, DRBD-data-packets.svg - relates some functions, and write packets. +.. toctree:: + :maxdepth: 1 -conn-states-8.dot, disk-states-8.dot, node-states-8.dot - The sub graphs of DRBD's state transitions + data-structure-v9 + figures diff --git a/Documentation/blockdev/floppy.txt b/Documentation/blockdev/floppy.rst index e2240f5ab64d..4a8f31cf4139 100644 --- a/Documentation/blockdev/floppy.txt +++ b/Documentation/blockdev/floppy.rst @@ -1,35 +1,37 @@ -This file describes the floppy driver. +============= +Floppy Driver +============= 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>. 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 configuration file. - Example: If your kernel is called linux-2.6.9, type the following line -at the lilo boot prompt (if you have a thinkpad): +Example: If your kernel is called linux-2.6.9, type the following line +at the lilo boot prompt (if you have a thinkpad):: linux-2.6.9 floppy=thinkpad 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" - 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 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 options coming last. That's why there are also options to restore the default behavior. @@ -38,21 +40,23 @@ restore the default behavior. Module configuration options ============================ - If you use the floppy driver as a module, use the following syntax: -modprobe floppy floppy="<options>" +If you use the floppy driver as a module, use the following syntax:: -Example: - modprobe floppy floppy="omnibook messages" + modprobe floppy floppy="<options>" - If you need certain options enabled every time you load the floppy driver, -you can put: +Example:: - 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/. - The floppy driver related options are: +The floppy driver related options are: floppy=asus_pci 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. (default) - floppy=two_fdc - floppy=<address>,two_fdc + floppy=two_fdc / floppy=<address>,two_fdc Tells the floppy driver that you have two floppy controllers. The second floppy controller is assumed to be 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 Tells the floppy driver that you don't have a Thinkpad. - floppy=omnibook - floppy=nodma + floppy=omnibook / floppy=nodma Tells the floppy driver not to use Dma for data transfers. This is needed on HP Omnibooks, which don't have a workable 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 non-standard CMOS types. The CMOS types are: - 0 - Use the value of the physical CMOS - 1 - 5 1/4 DD - 2 - 5 1/4 HD - 3 - 3 1/2 DD - 4 - 3 1/2 HD - 5 - 3 1/2 ED - 6 - 3 1/2 ED - 16 - unknown or not installed + == ================================== + 0 Use the value of the physical CMOS + 1 5 1/4 DD + 2 5 1/4 HD + 3 3 1/2 DD + 4 3 1/2 HD + 5 3 1/2 ED + 6 3 1/2 ED + 16 unknown or not installed + == ================================== (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. @@ -162,8 +166,7 @@ in a configuration file in /etc/modprobe.d/. Print a warning message when an unexpected interrupt is received. (default) - floppy=no_unexpected_interrupts - floppy=L40SX + floppy=no_unexpected_interrupts / floppy=L40SX Don't print a message when an unexpected interrupt is received. This is needed on IBM L40SX laptops in certain video modes. (There seems 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. floppy=slow - Use PS/2 stepping rate: - " PS/2 floppies have much slower step rates than regular floppies. + Use PS/2 stepping rate:: + + PS/2 floppies have much slower step rates than regular floppies. 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: ================================================== - 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. 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!). It also contains additional documentation about the floppy driver. The latest version can be found at fdutils homepage: + http://fdutils.linux.lu The fdutils releases can be found at: + http://fdutils.linux.lu/download.html + http://www.tux.org/pub/knaff/fdutils/ + ftp://metalab.unc.edu/pub/Linux/utils/disk-management/ 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 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 line. If the reported problem happens when mounting floppy disks, be 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 ========= -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> -6-3-2000 : Original Document +6-3-2000 : + Original Document diff --git a/Documentation/blockdev/index.rst b/Documentation/blockdev/index.rst new file mode 100644 index 000000000000..a9af6ed8b4aa --- /dev/null +++ b/Documentation/blockdev/index.rst @@ -0,0 +1,16 @@ +:orphan: + +=========================== +The Linux RapidIO Subsystem +=========================== + +.. toctree:: + :maxdepth: 1 + + floppy + nbd + paride + ramdisk + zram + + drbd/index diff --git a/Documentation/blockdev/nbd.txt b/Documentation/blockdev/nbd.rst index db242ea2bce8..d78dfe559dcf 100644 --- a/Documentation/blockdev/nbd.txt +++ b/Documentation/blockdev/nbd.rst @@ -1,3 +1,4 @@ +================================== Network Block Device (TCP version) ================================== @@ -28,4 +29,3 @@ max_part nbds_max Number of block devices that should be initialized (default: 16). - diff --git a/Documentation/blockdev/paride.txt b/Documentation/blockdev/paride.rst index ee6717e3771d..87b4278bf314 100644 --- a/Documentation/blockdev/paride.txt +++ b/Documentation/blockdev/paride.rst @@ -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> 1. Introduction +=============== Owing to the simplicity and near universality of the parallel port interface 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 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 a parallel-port adapter chip added in. Some of the original parallel port 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 that interconnected a standard PC parallel port cable and a standard 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 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: - MicroSolutions backpack CD-ROM - MicroSolutions backpack PD/CD - MicroSolutions backpack hard-drives - MicroSolutions backpack 8000t tape drive - SyQuest EZ-135, EZ-230 & SparQ drives - Avatar Shark - Imation Superdisk LS-120 - Maxell Superdisk LS-120 - FreeCom Power CD - Hewlett-Packard 5GB and 8GB tape drives - Hewlett-Packard 7100 and 7200 CD-RW drives + - MicroSolutions backpack CD-ROM + - MicroSolutions backpack PD/CD + - MicroSolutions backpack hard-drives + - MicroSolutions backpack 8000t tape drive + - SyQuest EZ-135, EZ-230 & SparQ drives + - Avatar Shark + - Imation Superdisk LS-120 + - Maxell Superdisk LS-120 + - FreeCom Power CD + - Hewlett-Packard 5GB and 8GB tape drives + - Hewlett-Packard 7100 and 7200 CD-RW drives 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 subsystem, is actually structured in three parts. There is a base paride module which provides a registry and some common methods for -accessing the parallel ports. The second component is a set of -high-level drivers for each of the different types of supported devices: +accessing the parallel ports. The second component is a set of +high-level drivers for each of the different types of supported devices: + === ============= pd IDE disk pcd ATAPI CD-ROM pf ATAPI disk pt ATAPI tape pg ATAPI generic + === ============= (Currently, the pg driver is only used with CD-R drives). The high-level drivers function according to the relevant standards. 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 -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: + ==== ====================================== ==== aten ATEN EH-100 (HK) bpck Microsolutions backpack (US) 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) on20 OnSpec 90c20 (US) on26 OnSpec 90c26 (US) + ==== ====================================== ==== 2. Using the PARIDE subsystem +============================= While configuring the Linux kernel, you may choose either to build 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 of the parallel port communication protocols. If you do not know 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 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 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 and high-level drivers that you would use: + ================ ============ ====== ======== Manufacturer Model Driver Protocol - + ================ ============ ====== ======== MicroSolutions CD-ROM pcd bpck MicroSolutions PD drive pf 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 7200e (CD) pcd epat Hewlett-Packard 7200e (CD-R) pg epat + ================ ============ ====== ======== 2.1 Configuring built-in drivers +--------------------------------- We recommend that you get to know how the drivers work and how to 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 displayed on the console. Like all such messages, they can be reviewed with the 'dmesg' command. Among those messages will be -some lines like: +some lines like:: paride: bpck registered as protocol 0 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). 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 -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 -options on your boot command: +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 +Imation Superdisk connected to port 0x278. You could give the following +options on your boot command:: 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 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 "Parallel port support" option, PARPORT must be included and enabled if you want to use chains of devices on the same parallel port. 2.2 Loading and configuring PARIDE as modules +---------------------------------------------- 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 -system is not recommended for beginners, and is not documented here. +Note 1: + 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 -also be built as loadable modules, and PARPORT must be loaded before the -PARIDE modules. +Note 2: + if you build PARPORT support as a loadable module, PARIDE must + 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 @@ -195,8 +208,8 @@ among other tasks. 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, -and print a log message to your kernel log file and your console. For -example: +and print a log message to your kernel log file and your console. For +example:: # insmod epat paride: epat registered as protocol 0 @@ -205,22 +218,22 @@ example: paride: k971 registered as protocol 2 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 individual co-ordinates when you load the driver. 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 -you could give the following command: +you could give the following command:: # insmod pcd drive0=0x378,1 drive1=0x3bc,1 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 !). 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 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. 2.3 Using a PARIDE device +-------------------------- Once the drivers have been loaded, you can access PARIDE devices in the same way as their traditional counterparts. You will probably need to create the device "special files". Here is a simple script that you can -cut to a file and execute: - -#!/bin/bash -# -# mkd -- a script to create the device special files for the PARIDE subsystem -# -function mkdev { - mknod $1 $2 $3 $4 ; chmod 0660 $1 ; chown root:disk $1 -} -# -function pd { - D=$( printf \\$( printf "x%03x" $[ $1 + 97 ] ) ) - mkdev pd$D b 45 $[ $1 * 16 ] - for P in 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 - do mkdev pd$D$P b 45 $[ $1 * 16 + $P ] - done -} -# -cd /dev -# -for u in 0 1 2 3 ; do pd $u ; done -for u in 0 1 2 3 ; do mkdev pcd$u b 46 $u ; done -for u in 0 1 2 3 ; do mkdev pf$u b 47 $u ; done -for u in 0 1 2 3 ; do mkdev pt$u c 96 $u ; done -for u in 0 1 2 3 ; do mkdev npt$u c 96 $[ $u + 128 ] ; done -for u in 0 1 2 3 ; do mkdev pg$u c 97 $u ; done -# -# end of mkd +cut to a file and execute:: + + #!/bin/bash + # + # mkd -- a script to create the device special files for the PARIDE subsystem + # + function mkdev { + mknod $1 $2 $3 $4 ; chmod 0660 $1 ; chown root:disk $1 + } + # + function pd { + D=$( printf \\$( printf "x%03x" $[ $1 + 97 ] ) ) + mkdev pd$D b 45 $[ $1 * 16 ] + for P in 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 + do mkdev pd$D$P b 45 $[ $1 * 16 + $P ] + done + } + # + cd /dev + # + for u in 0 1 2 3 ; do pd $u ; done + for u in 0 1 2 3 ; do mkdev pcd$u b 46 $u ; done + for u in 0 1 2 3 ; do mkdev pf$u b 47 $u ; done + for u in 0 1 2 3 ; do mkdev pt$u c 96 $u ; done + for u in 0 1 2 3 ; do mkdev npt$u c 96 $[ $u + 128 ] ; done + for u in 0 1 2 3 ; do mkdev pg$u c 97 $u ; done + # + # end of mkd 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 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 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 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 mount /dev/pf0 /mnt 2.4 The pf driver +------------------ The pf driver is intended for use with parallel port ATAPI disk devices. The most common devices in this category are PD drives and LS-120 drives. Traditionally, media for these devices are not 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 +------------------------ 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 probably want to set the parallel port delay to 0, if you can. 2.6 Using the pg driver +------------------------ 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 -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" -should be set to 0. With those settings it is possible to record at 2x +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" +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 in EPP mode, try to use "bidirectional" or "PS/2" mode and 1x speeds only. 3. Troubleshooting +================== 3.1 Use EPP mode if you can +---------------------------- The most common problems that people report with the PARIDE drivers 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. 3.2 Check the port delay +------------------------- Some parallel ports cannot reliably transfer data at full speed. To 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. 3.3 Some drives need a printer reset +------------------------------------- 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 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 parallel port. As the reset operation is potentially disruptive in -multiple device environments, the PARIDE drivers will not do it -automatically. You can however, force a printer reset by doing: +the parallel port. As the reset operation is potentially disruptive in +multiple device environments, the PARIDE drivers will not do it +automatically. You can however, force a printer reset by doing:: insmod lp reset=1 rmmod lp If you have one of these marginal cases, you should probably build 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 +------------------------------------------------------ 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, @@ -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 is using your parallel port (check in /proc/ioports). Then, load the appropriate drivers (you can load several protocol modules if you want) -as in: +as in:: # insmod paride # 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. 3.5 For more information or help +--------------------------------- You can join the linux-parport mailing list by sending a mail message -to +to: + linux-parport-request@torque.net -with the single word +with the single word:: 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 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/ diff --git a/Documentation/blockdev/ramdisk.txt b/Documentation/blockdev/ramdisk.rst index 501e12e0323e..b7c2268f8dec 100644 --- a/Documentation/blockdev/ramdisk.txt +++ b/Documentation/blockdev/ramdisk.rst @@ -1,7 +1,8 @@ +========================================== Using the RAM disk block device with Linux ------------------------------------------- +========================================== -Contents: +.. Contents: 1) Overview 2) Kernel Command Line Parameters @@ -42,7 +43,7 @@ rescue floppy disk. 2a) Kernel Command Line Parameters ramdisk_size=N - ============== + Size of the ramdisk. This parameter tells the RAM disk driver to set up RAM disks of N k size. The default is 4096 (4 MB). @@ -50,16 +51,13 @@ default is 4096 (4 MB). 2b) Module parameters rd_nr - ===== - /dev/ramX devices created. + /dev/ramX devices created. max_part - ======== - Maximum partition number. + Maximum partition number. rd_size - ======= - See ramdisk_size. + See ramdisk_size. 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 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. -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_PROMPT_FLAG 0x8000 -./arch/x86/kernel/setup.c:#define RAMDISK_LOAD_FLAG 0x4000 + ./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_LOAD_FLAG 0x4000 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. @@ -92,20 +90,23 @@ sequence so that you have a chance to switch floppy disks. The command line equivalent is: "prompt_ramdisk=1" 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# rdev /dev/fd0 /dev/fd0 /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" -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" 4) An Example of Creating a Compressed RAM Disk ----------------------------------------------- +----------------------------------------------- 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 @@ -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 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 - 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 -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 @@ -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 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 -e) Put the kernel onto the floppy +e) Put the kernel onto the floppy:: 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 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 - 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 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 - have 2^15 + 2^14 + 400 = 49552. + have 2^15 + 2^14 + 400 = 49552:: rdev /dev/fd0 /dev/fd0 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 users may wish to combine steps (d) and (f) by using a pipe. --------------------------------------------------------------------------- + Paul Gortmaker 12/95 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. James Nelson (james4765@gmail.com) -12-95 : Original Document +12-95 : + Original Document diff --git a/Documentation/blockdev/zram.txt b/Documentation/blockdev/zram.rst index 4df0ce271085..2111231c9c0f 100644 --- a/Documentation/blockdev/zram.txt +++ b/Documentation/blockdev/zram.rst @@ -1,7 +1,9 @@ +======================================== zram: Compressed RAM based block devices ----------------------------------------- +======================================== -* Introduction +Introduction +============ The zram module creates RAM based block devices named /dev/zram<id> (<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 /sys/block/zram<id>/ -* Usage +Usage +===== There are several ways to configure and manage zram device(-s): + a) using zram and zram_control sysfs attributes 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. 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 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 ======= + 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. zram sysfs attributes always return negative values in case of errors. 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 -needs; --EINVAL -- invalid input has been provided. + +======== ============================================================= +-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 + needs; +-EINVAL invalid input has been provided. +======== ============================================================= 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 if [ $? -ne 0 ]; @@ -51,7 +59,11 @@ and, in general case, something like: should suffice. -1) Load Module: +1) Load Module +============== + +:: + modprobe zram num_devices=4 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. 2) Set max number of compression streams +======================================== + Regardless the value passed to this attribute, ZRAM will always allocate multiple compression streams - one per online CPUs - thus 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, 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 3) Select compression algorithm +=============================== + Using comp_algorithm device attribute one can see available and currently selected (shown in square brackets) compression algorithms, change selected compression algorithm (once the device is initialised there is no way to change compression algorithm). -Examples: +Examples:: + #show supported compression algorithms cat /sys/block/zram0/comp_algorithm lzo [lz4] @@ -83,20 +101,23 @@ Examples: #select lzo compression 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 list primarily to simplify device configuration and one can configure 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 to list all of them using, for instance, /proc/crypto or any other method. This, however, has an advantage of permitting the usage of custom crypto compression modules (implementing S/W or H/W compression). 4) Set 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. -Examples: +Examples:: + # Initialize /dev/zram0 with 50MB 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. 5) Set memory limit: Optional +============================= + 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. In addition, you could change the value in runtime. -Examples: +Examples:: + # limit /dev/zram0 with 50MB memory echo $((50*1024*1024)) > /sys/block/zram0/mem_limit @@ -126,7 +150,11 @@ Examples: # To disable memory limit echo 0 > /sys/block/zram0/mem_limit -6) Activate: +6) Activate +=========== + +:: + mkswap /dev/zram0 swapon /dev/zram0 @@ -134,6 +162,7 @@ Examples: mount /dev/zram1 /tmp 7) Add/remove zram devices +========================== zram provides a control interface, which enables dynamic (on-demand) device 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 can use /dev/zram<id>) or error code. -Example: +Example:: + cat /sys/class/zram-control/hot_add 1 To remove the existing /dev/zramX device (where X is a device id) -execute +execute:: + 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>/ A brief description of exported device attributes. For more details please read Documentation/ABI/testing/sysfs-block-zram. +====================== ====== =============================================== Name access description ----- ------ ----------- +====================== ====== =============================================== disksize RW show and set the device's disk size initstate RO shows the initialization state of the device reset WO trigger device reset -mem_used_max WO reset the `mem_used_max' counter (see later) -mem_limit WO specifies the maximum amount of memory ZRAM can use - to store the compressed data -writeback_limit WO specifies the maximum amount of write IO zram can - write out to backing device as 4KB unit +mem_used_max WO reset the `mem_used_max` counter (see later) +mem_limit WO specifies the maximum amount of memory ZRAM can + use to store the compressed data +writeback_limit WO specifies the maximum amount of write IO zram + can write out to backing device as 4KB unit 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 compact WO trigger memory compaction debug_stat RO this file is used for zram debugging purposes backing_dev RW set up backend storage for zram to write out idle WO mark allocated slot as idle +====================== ====== =============================================== 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 single line of text and contains the following stats separated by 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 + a) the number of pages freed because of swap slot free - notifications or b) the number of pages freed because of - REQ_OP_DISCARD requests sent by bio. The former ones are - sent to a swap block device when a swap slot is freed, - which implies that this disk is being used as a swap disk. + notifications + b) the number of pages freed because of + REQ_OP_DISCARD requests sent by bio. The former ones are + 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 discard option, whenever some data blocks are getting discarded. + ============= ============================================================= File /sys/block/zram<id>/mm_stat The stat file represents device's mm statistics. It consists of a single line of text and contains the following stats separated by whitespace: + + ================ ============================================================= orig_data_size uncompressed size of data stored in this disk. This excludes same-element-filled pages (same_pages) since 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. pages_compacted the number of pages freed during compaction huge_pages the number of incompressible pages + ================ ============================================================= File /sys/block/zram<id>/bd_stat 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: + + ============== ============================================================= bd_count size of data written in backing device. Unit: 4K bytes bd_reads the number of reads from backing device Unit: 4K bytes bd_writes the number of writes to backing device Unit: 4K bytes + ============== ============================================================= + +9) Deactivate +============= + +:: -9) Deactivate: swapoff /dev/zram0 umount /dev/zram1 -10) Reset: - Write any positive value to 'reset' sysfs node - echo 1 > /sys/block/zram0/reset - echo 1 > /sys/block/zram1/reset +10) 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 resets the disksize to zero. You must set the disksize again before reusing the device. -* Optional Feature +Optional Feature +================ -= writeback +writeback +--------- With CONFIG_ZRAM_WRITEBACK, zram can write idle/incompressible page 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. -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 -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 will be removed until someone request access of the block. 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. @@ -285,7 +342,7 @@ to guarantee storage health for entire product life. To overcome the concern, zram supports "writeback_limit" feature. 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 -enable writeback_limit_enable via +enable writeback_limit_enable via:: $ 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.) If admin want to limit writeback as per-day 400M, he could do it -like below. +like below:: $ MB_SHIFT=20 $ 4K_SHIFT=12 @@ -305,16 +362,16 @@ like below. $ echo 1 > /sys/block/zram0/writeback_limit_enable 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)) > \ /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 -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 @@ -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 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 zram block. It could be useful to catch cold or incompressible pages of the process with*pagemap. + 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. 301 63.806904 s... 302 63.806919 ..hi -First column is zram's block index. -Second column is access time since the system was booted -Third column is state of the block. -(s: same page -w: written page to backing store -h: huge page -i: idle page) +First column + zram's block index. +Second column + access time since the system was booted +Third column + state of the block: + + 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 and the block's state is huge so it is written back to the backing |