linux-toradex.git/Documentation/blockdev, branch v3.14.3

zram: remove old private project comment

2014-01-31T00:56:55+00:00

Remove the old private compcache project address so upcoming patches
should be sent to LKML because we Linux kernel community will take care.

Signed-off-by: Minchan Kim 
Cc: Nitin Gupta 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

zram: promote zram from staging

2014-01-31T00:56:55+00:00

Zram has lived in staging for a LONG LONG time and have been
fixed/improved by many contributors so code is clean and stable now.  Of
course, there are lots of product using zram in real practice.

The major TV companys have used zram as swap since two years ago and
recently our production team released android smart phone with zram
which is used as swap, too and recently Android Kitkat start to use zram
for small memory smart phone.  And there was a report Google released
their ChromeOS with zram, too and cyanogenmod have been used zram long
time ago.  And I heard some disto have used zram block device for tmpfs.
In addition, I saw many report from many other peoples.  For example,
Lubuntu start to use it.

The benefit of zram is very clear.  With my experience, one of the
benefit was to remove jitter of video application with backgroud memory
pressure.  It would be effect of efficient memory usage by compression
but more issue is whether swap is there or not in the system.  Recent
mobile platforms have used JAVA so there are many anonymous pages.  But
embedded system normally are reluctant to use eMMC or SDCard as swap
because there is wear-leveling and latency issues so if we do not use
swap, it means we can't reclaim anoymous pages and at last, we could
encounter OOM kill.  :(

Although we have real storage as swap, it was a problem, too.  Because
it sometime ends up making system very unresponsible caused by slow swap
storage performance.

Quote from Luigi on Google
 "Since Chrome OS was mentioned: the main reason why we don't use swap
  to a disk (rotating or SSD) is because it doesn't degrade gracefully
  and leads to a bad interactive experience.  Generally we prefer to
  manage RAM at a higher level, by transparently killing and restarting
  processes.  But we noticed that zram is fast enough to be competitive
  with the latter, and it lets us make more efficient use of the
  available RAM.  " and he announced.
http://www.spinics.net/lists/linux-mm/msg57717.html

Other uses case is to use zram for block device.  Zram is block device
so anyone can format the block device and mount on it so some guys on
the internet start zram as /var/tmp.
http://forums.gentoo.org/viewtopic-t-838198-start-0.html

Let's promote zram and enhance/maintain it instead of removing.

Signed-off-by: Minchan Kim 
Reviewed-by: Konrad Rzeszutek Wilk 
Acked-by: Nitin Gupta 
Acked-by: Pekka Enberg 
Cc: Bob Liu 
Cc: Greg Kroah-Hartman 
Cc: Hugh Dickins 
Cc: Jens Axboe 
Cc: Luigi Semenzato 
Cc: Mel Gorman 
Cc: Rik van Riel 
Cc: Seth Jennings 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Documentation/blockdev/ramdisk.txt: updates

2014-01-24T00:37:01+00:00

- ramdisk_blocksize doesn't exist anymore

- Module parameters added to documentation

Signed-off-by: Fabian Frederick 
Acked-by: Randy Dunlap 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

floppy: Correct documentation of driver options when used as a module.

2013-11-08T16:10:31+00:00

The options have to be passed space-separated and prefixed by "floppy=",
rather than separately and unprefixed.

This fixes .

Signed-off-by: Ben Harris 
Signed-off-by: Jiri Kosina

nbd: update documentation and link to mailinglist

2013-02-28T03:10:22+00:00

Documentation/blockdev/nbd.txt contained some documentation which was
horribly outdated and probably still dates from the original patch that
added NBD support to the kernel.

This patch removes the useless and outdated bits.  The tools on nbd.sf.net
are fully documented in manpages, which is where documentation for the
non-kernel bits should live.

Additionally, add a reference to the MAINTAINERS file for the nbd-general
mailinglist that is used for discussion of the userland tools and the
kernel module already.

Signed-off-by: Wouter Verhelst 
Cc: Paul Clements 
Cc: Paolo Bonzini 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Documentation: remove references to /etc/modprobe.conf

2012-03-30T23:03:15+00:00

Usage of /etc/modprobe.conf file was deprecated by module-init-tools and
is no longer parsed by new kmod tool. References to this file are
replaced in Documentation, comments and Kconfig according to the
context.

There are also some references to the old /etc/modules.conf from 2.4
kernels that are being removed.

Signed-off-by: Lucas De Marchi 
Acked-by: Takashi Iwai 
Acked-by: Mauro Carvalho Chehab 
Signed-off-by: Randy Dunlap 
Signed-off-by: Linus Torvalds

cciss: auto engage SCSI mid layer at driver load time

2011-11-16T08:21:49+00:00

A long time ago, probably in 2002, one of the distros, or maybe more than
one, loaded block drivers prior to loading the SCSI mid layer.  This meant
that the cciss driver, being a block driver, could not engage the SCSI mid
layer at init time without panicking, and relied on being poked by a
userland program after the system was up (and the SCSI mid layer was
therefore present) to engage the SCSI mid layer.

This is no longer the case, and cciss can safely rely on the SCSI mid
layer being present at init time and engage the SCSI mid layer straight
away.  This means that users will see their tape drives and medium
changers at driver load time without need for a script in /etc/rc.d that
does this:

for x in /proc/driver/cciss/cciss*
do
	echo "engage scsi" > $x
done

However, if no tape drives or medium changers are detected, the SCSI mid
layer will not be engaged.  If a tape drive or medium change is later
hot-added to the system it will then be necessary to use the above script
or similar for the device(s) to be acceesible.

Signed-off-by: Stephen M. Cameron 
Signed-off-by: Andrew Morton 
Signed-off-by: Jens Axboe

cciss: Adds simple mode functionality

2011-08-08T09:40:15+00:00

Signed-off-by: Joseph Handzik 
Acked-by: Stephen M. Cameron 
Signed-off-by: Jens Axboe

doc: fix wrong arch/i386 references

2011-06-13T11:43:05+00:00

Change all "arch/i386" to "arch/x86" in Documentaion/,
since the directory has changed.

Also update the files which have changed their filename
in the meantime accordingly.

Signed-off-by: Wanlong Gao 
[jkosina@suse.cz: reword changelog]
Signed-off-by: Jiri Kosina

cciss: add cciss_tape_cmds module paramter

2011-05-06T14:23:59+00:00

This is to allow number of commands reserved for use by SCSI tape drives
and medium changers to be adjusted at driver load time via the kernel
parameter cciss_tape_cmds, with a default value of 6, and a range
of 2 - 16 inclusive.  Previously, the driver limited the number of
commands which could be queued to the SCSI half of the the driver
to only 2.  This is to fix the problem that if you had more than
two tape drives, you couldn't, for example, erase or rewind them all
at the same time.

Signed-off-by: Stephen M. Cameron 
Signed-off-by: Jens Axboe