forked from luck/tmp_suning_uos_patched
90f2447d08
Minor update to Documentation/applying-patches.txt Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
447 lines
19 KiB
Plaintext
447 lines
19 KiB
Plaintext
|
|
Applying Patches To The Linux Kernel
|
|
------------------------------------
|
|
|
|
Original by: Jesper Juhl, August 2005
|
|
Last update: 2005-12-02
|
|
|
|
|
|
|
|
A frequently asked question on the Linux Kernel Mailing List is how to apply
|
|
a patch to the kernel or, more specifically, what base kernel a patch for
|
|
one of the many trees/branches should be applied to. Hopefully this document
|
|
will explain this to you.
|
|
|
|
In addition to explaining how to apply and revert patches, a brief
|
|
description of the different kernel trees (and examples of how to apply
|
|
their specific patches) is also provided.
|
|
|
|
|
|
What is a patch?
|
|
---
|
|
A patch is a small text document containing a delta of changes between two
|
|
different versions of a source tree. Patches are created with the `diff'
|
|
program.
|
|
To correctly apply a patch you need to know what base it was generated from
|
|
and what new version the patch will change the source tree into. These
|
|
should both be present in the patch file metadata or be possible to deduce
|
|
from the filename.
|
|
|
|
|
|
How do I apply or revert a patch?
|
|
---
|
|
You apply a patch with the `patch' program. The patch program reads a diff
|
|
(or patch) file and makes the changes to the source tree described in it.
|
|
|
|
Patches for the Linux kernel are generated relative to the parent directory
|
|
holding the kernel source dir.
|
|
|
|
This means that paths to files inside the patch file contain the name of the
|
|
kernel source directories it was generated against (or some other directory
|
|
names like "a/" and "b/").
|
|
Since this is unlikely to match the name of the kernel source dir on your
|
|
local machine (but is often useful info to see what version an otherwise
|
|
unlabeled patch was generated against) you should change into your kernel
|
|
source directory and then strip the first element of the path from filenames
|
|
in the patch file when applying it (the -p1 argument to `patch' does this).
|
|
|
|
To revert a previously applied patch, use the -R argument to patch.
|
|
So, if you applied a patch like this:
|
|
patch -p1 < ../patch-x.y.z
|
|
|
|
You can revert (undo) it like this:
|
|
patch -R -p1 < ../patch-x.y.z
|
|
|
|
|
|
How do I feed a patch/diff file to `patch'?
|
|
---
|
|
This (as usual with Linux and other UNIX like operating systems) can be
|
|
done in several different ways.
|
|
In all the examples below I feed the file (in uncompressed form) to patch
|
|
via stdin using the following syntax:
|
|
patch -p1 < path/to/patch-x.y.z
|
|
|
|
If you just want to be able to follow the examples below and don't want to
|
|
know of more than one way to use patch, then you can stop reading this
|
|
section here.
|
|
|
|
Patch can also get the name of the file to use via the -i argument, like
|
|
this:
|
|
patch -p1 -i path/to/patch-x.y.z
|
|
|
|
If your patch file is compressed with gzip or bzip2 and you don't want to
|
|
uncompress it before applying it, then you can feed it to patch like this
|
|
instead:
|
|
zcat path/to/patch-x.y.z.gz | patch -p1
|
|
bzcat path/to/patch-x.y.z.bz2 | patch -p1
|
|
|
|
If you wish to uncompress the patch file by hand first before applying it
|
|
(what I assume you've done in the examples below), then you simply run
|
|
gunzip or bunzip2 on the file - like this:
|
|
gunzip patch-x.y.z.gz
|
|
bunzip2 patch-x.y.z.bz2
|
|
|
|
Which will leave you with a plain text patch-x.y.z file that you can feed to
|
|
patch via stdin or the -i argument, as you prefer.
|
|
|
|
A few other nice arguments for patch are -s which causes patch to be silent
|
|
except for errors which is nice to prevent errors from scrolling out of the
|
|
screen too fast, and --dry-run which causes patch to just print a listing of
|
|
what would happen, but doesn't actually make any changes. Finally --verbose
|
|
tells patch to print more information about the work being done.
|
|
|
|
|
|
Common errors when patching
|
|
---
|
|
When patch applies a patch file it attempts to verify the sanity of the
|
|
file in different ways.
|
|
Checking that the file looks like a valid patch file, checking the code
|
|
around the bits being modified matches the context provided in the patch are
|
|
just two of the basic sanity checks patch does.
|
|
|
|
If patch encounters something that doesn't look quite right it has two
|
|
options. It can either refuse to apply the changes and abort or it can try
|
|
to find a way to make the patch apply with a few minor changes.
|
|
|
|
One example of something that's not 'quite right' that patch will attempt to
|
|
fix up is if all the context matches, the lines being changed match, but the
|
|
line numbers are different. This can happen, for example, if the patch makes
|
|
a change in the middle of the file but for some reasons a few lines have
|
|
been added or removed near the beginning of the file. In that case
|
|
everything looks good it has just moved up or down a bit, and patch will
|
|
usually adjust the line numbers and apply the patch.
|
|
|
|
Whenever patch applies a patch that it had to modify a bit to make it fit
|
|
it'll tell you about it by saying the patch applied with 'fuzz'.
|
|
You should be wary of such changes since even though patch probably got it
|
|
right it doesn't /always/ get it right, and the result will sometimes be
|
|
wrong.
|
|
|
|
When patch encounters a change that it can't fix up with fuzz it rejects it
|
|
outright and leaves a file with a .rej extension (a reject file). You can
|
|
read this file to see exactly what change couldn't be applied, so you can
|
|
go fix it up by hand if you wish.
|
|
|
|
If you don't have any third party patches applied to your kernel source, but
|
|
only patches from kernel.org and you apply the patches in the correct order,
|
|
and have made no modifications yourself to the source files, then you should
|
|
never see a fuzz or reject message from patch. If you do see such messages
|
|
anyway, then there's a high risk that either your local source tree or the
|
|
patch file is corrupted in some way. In that case you should probably try
|
|
re-downloading the patch and if things are still not OK then you'd be advised
|
|
to start with a fresh tree downloaded in full from kernel.org.
|
|
|
|
Let's look a bit more at some of the messages patch can produce.
|
|
|
|
If patch stops and presents a "File to patch:" prompt, then patch could not
|
|
find a file to be patched. Most likely you forgot to specify -p1 or you are
|
|
in the wrong directory. Less often, you'll find patches that need to be
|
|
applied with -p0 instead of -p1 (reading the patch file should reveal if
|
|
this is the case - if so, then this is an error by the person who created
|
|
the patch but is not fatal).
|
|
|
|
If you get "Hunk #2 succeeded at 1887 with fuzz 2 (offset 7 lines)." or a
|
|
message similar to that, then it means that patch had to adjust the location
|
|
of the change (in this example it needed to move 7 lines from where it
|
|
expected to make the change to make it fit).
|
|
The resulting file may or may not be OK, depending on the reason the file
|
|
was different than expected.
|
|
This often happens if you try to apply a patch that was generated against a
|
|
different kernel version than the one you are trying to patch.
|
|
|
|
If you get a message like "Hunk #3 FAILED at 2387.", then it means that the
|
|
patch could not be applied correctly and the patch program was unable to
|
|
fuzz its way through. This will generate a .rej file with the change that
|
|
caused the patch to fail and also a .orig file showing you the original
|
|
content that couldn't be changed.
|
|
|
|
If you get "Reversed (or previously applied) patch detected! Assume -R? [n]"
|
|
then patch detected that the change contained in the patch seems to have
|
|
already been made.
|
|
If you actually did apply this patch previously and you just re-applied it
|
|
in error, then just say [n]o and abort this patch. If you applied this patch
|
|
previously and actually intended to revert it, but forgot to specify -R,
|
|
then you can say [y]es here to make patch revert it for you.
|
|
This can also happen if the creator of the patch reversed the source and
|
|
destination directories when creating the patch, and in that case reverting
|
|
the patch will in fact apply it.
|
|
|
|
A message similar to "patch: **** unexpected end of file in patch" or "patch
|
|
unexpectedly ends in middle of line" means that patch could make no sense of
|
|
the file you fed to it. Either your download is broken or you tried to feed
|
|
patch a compressed patch file without uncompressing it first.
|
|
|
|
As I already mentioned above, these errors should never happen if you apply
|
|
a patch from kernel.org to the correct version of an unmodified source tree.
|
|
So if you get these errors with kernel.org patches then you should probably
|
|
assume that either your patch file or your tree is broken and I'd advice you
|
|
to start over with a fresh download of a full kernel tree and the patch you
|
|
wish to apply.
|
|
|
|
|
|
Are there any alternatives to `patch'?
|
|
---
|
|
Yes there are alternatives.
|
|
|
|
You can use the `interdiff' program (http://cyberelk.net/tim/patchutils/) to
|
|
generate a patch representing the differences between two patches and then
|
|
apply the result.
|
|
This will let you move from something like 2.6.12.2 to 2.6.12.3 in a single
|
|
step. The -z flag to interdiff will even let you feed it patches in gzip or
|
|
bzip2 compressed form directly without the use of zcat or bzcat or manual
|
|
decompression.
|
|
|
|
Here's how you'd go from 2.6.12.2 to 2.6.12.3 in a single step:
|
|
interdiff -z ../patch-2.6.12.2.bz2 ../patch-2.6.12.3.gz | patch -p1
|
|
|
|
Although interdiff may save you a step or two you are generally advised to
|
|
do the additional steps since interdiff can get things wrong in some cases.
|
|
|
|
Another alternative is `ketchup', which is a python script for automatic
|
|
downloading and applying of patches (http://www.selenic.com/ketchup/).
|
|
|
|
Other nice tools are diffstat which shows a summary of changes made by a
|
|
patch, lsdiff which displays a short listing of affected files in a patch
|
|
file, along with (optionally) the line numbers of the start of each patch
|
|
and grepdiff which displays a list of the files modified by a patch where
|
|
the patch contains a given regular expression.
|
|
|
|
|
|
Where can I download the patches?
|
|
---
|
|
The patches are available at http://kernel.org/
|
|
Most recent patches are linked from the front page, but they also have
|
|
specific homes.
|
|
|
|
The 2.6.x.y (-stable) and 2.6.x patches live at
|
|
ftp://ftp.kernel.org/pub/linux/kernel/v2.6/
|
|
|
|
The -rc patches live at
|
|
ftp://ftp.kernel.org/pub/linux/kernel/v2.6/testing/
|
|
|
|
The -git patches live at
|
|
ftp://ftp.kernel.org/pub/linux/kernel/v2.6/snapshots/
|
|
|
|
The -mm kernels live at
|
|
ftp://ftp.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/
|
|
|
|
In place of ftp.kernel.org you can use ftp.cc.kernel.org, where cc is a
|
|
country code. This way you'll be downloading from a mirror site that's most
|
|
likely geographically closer to you, resulting in faster downloads for you,
|
|
less bandwidth used globally and less load on the main kernel.org servers -
|
|
these are good things, do use mirrors when possible.
|
|
|
|
|
|
The 2.6.x kernels
|
|
---
|
|
These are the base stable releases released by Linus. The highest numbered
|
|
release is the most recent.
|
|
|
|
If regressions or other serious flaws are found then a -stable fix patch
|
|
will be released (see below) on top of this base. Once a new 2.6.x base
|
|
kernel is released, a patch is made available that is a delta between the
|
|
previous 2.6.x kernel and the new one.
|
|
|
|
To apply a patch moving from 2.6.11 to 2.6.12 you'd do the following (note
|
|
that such patches do *NOT* apply on top of 2.6.x.y kernels but on top of the
|
|
base 2.6.x kernel - if you need to move from 2.6.x.y to 2.6.x+1 you need to
|
|
first revert the 2.6.x.y patch).
|
|
|
|
Here are some examples:
|
|
|
|
# moving from 2.6.11 to 2.6.12
|
|
$ cd ~/linux-2.6.11 # change to kernel source dir
|
|
$ patch -p1 < ../patch-2.6.12 # apply the 2.6.12 patch
|
|
$ cd ..
|
|
$ mv linux-2.6.11 linux-2.6.12 # rename source dir
|
|
|
|
# moving from 2.6.11.1 to 2.6.12
|
|
$ cd ~/linux-2.6.11.1 # change to kernel source dir
|
|
$ patch -p1 -R < ../patch-2.6.11.1 # revert the 2.6.11.1 patch
|
|
# source dir is now 2.6.11
|
|
$ patch -p1 < ../patch-2.6.12 # apply new 2.6.12 patch
|
|
$ cd ..
|
|
$ mv linux-2.6.11.1 linux-2.6.12 # rename source dir
|
|
|
|
|
|
The 2.6.x.y kernels
|
|
---
|
|
Kernels with 4 digit versions are -stable kernels. They contain small(ish)
|
|
critical fixes for security problems or significant regressions discovered
|
|
in a given 2.6.x kernel.
|
|
|
|
This is the recommended branch for users who want the most recent stable
|
|
kernel and are not interested in helping test development/experimental
|
|
versions.
|
|
|
|
If no 2.6.x.y kernel is available, then the highest numbered 2.6.x kernel is
|
|
the current stable kernel.
|
|
|
|
These patches are not incremental, meaning that for example the 2.6.12.3
|
|
patch does not apply on top of the 2.6.12.2 kernel source, but rather on top
|
|
of the base 2.6.12 kernel source.
|
|
So, in order to apply the 2.6.12.3 patch to your existing 2.6.12.2 kernel
|
|
source you have to first back out the 2.6.12.2 patch (so you are left with a
|
|
base 2.6.12 kernel source) and then apply the new 2.6.12.3 patch.
|
|
|
|
Here's a small example:
|
|
|
|
$ cd ~/linux-2.6.12.2 # change into the kernel source dir
|
|
$ patch -p1 -R < ../patch-2.6.12.2 # revert the 2.6.12.2 patch
|
|
$ patch -p1 < ../patch-2.6.12.3 # apply the new 2.6.12.3 patch
|
|
$ cd ..
|
|
$ mv linux-2.6.12.2 linux-2.6.12.3 # rename the kernel source dir
|
|
|
|
|
|
The -rc kernels
|
|
---
|
|
These are release-candidate kernels. These are development kernels released
|
|
by Linus whenever he deems the current git (the kernel's source management
|
|
tool) tree to be in a reasonably sane state adequate for testing.
|
|
|
|
These kernels are not stable and you should expect occasional breakage if
|
|
you intend to run them. This is however the most stable of the main
|
|
development branches and is also what will eventually turn into the next
|
|
stable kernel, so it is important that it be tested by as many people as
|
|
possible.
|
|
|
|
This is a good branch to run for people who want to help out testing
|
|
development kernels but do not want to run some of the really experimental
|
|
stuff (such people should see the sections about -git and -mm kernels below).
|
|
|
|
The -rc patches are not incremental, they apply to a base 2.6.x kernel, just
|
|
like the 2.6.x.y patches described above. The kernel version before the -rcN
|
|
suffix denotes the version of the kernel that this -rc kernel will eventually
|
|
turn into.
|
|
So, 2.6.13-rc5 means that this is the fifth release candidate for the 2.6.13
|
|
kernel and the patch should be applied on top of the 2.6.12 kernel source.
|
|
|
|
Here are 3 examples of how to apply these patches:
|
|
|
|
# first an example of moving from 2.6.12 to 2.6.13-rc3
|
|
$ cd ~/linux-2.6.12 # change into the 2.6.12 source dir
|
|
$ patch -p1 < ../patch-2.6.13-rc3 # apply the 2.6.13-rc3 patch
|
|
$ cd ..
|
|
$ mv linux-2.6.12 linux-2.6.13-rc3 # rename the source dir
|
|
|
|
# now let's move from 2.6.13-rc3 to 2.6.13-rc5
|
|
$ cd ~/linux-2.6.13-rc3 # change into the 2.6.13-rc3 dir
|
|
$ patch -p1 -R < ../patch-2.6.13-rc3 # revert the 2.6.13-rc3 patch
|
|
$ patch -p1 < ../patch-2.6.13-rc5 # apply the new 2.6.13-rc5 patch
|
|
$ cd ..
|
|
$ mv linux-2.6.13-rc3 linux-2.6.13-rc5 # rename the source dir
|
|
|
|
# finally let's try and move from 2.6.12.3 to 2.6.13-rc5
|
|
$ cd ~/linux-2.6.12.3 # change to the kernel source dir
|
|
$ patch -p1 -R < ../patch-2.6.12.3 # revert the 2.6.12.3 patch
|
|
$ patch -p1 < ../patch-2.6.13-rc5 # apply new 2.6.13-rc5 patch
|
|
$ cd ..
|
|
$ mv linux-2.6.12.3 linux-2.6.13-rc5 # rename the kernel source dir
|
|
|
|
|
|
The -git kernels
|
|
---
|
|
These are daily snapshots of Linus' kernel tree (managed in a git
|
|
repository, hence the name).
|
|
|
|
These patches are usually released daily and represent the current state of
|
|
Linus' tree. They are more experimental than -rc kernels since they are
|
|
generated automatically without even a cursory glance to see if they are
|
|
sane.
|
|
|
|
-git patches are not incremental and apply either to a base 2.6.x kernel or
|
|
a base 2.6.x-rc kernel - you can see which from their name.
|
|
A patch named 2.6.12-git1 applies to the 2.6.12 kernel source and a patch
|
|
named 2.6.13-rc3-git2 applies to the source of the 2.6.13-rc3 kernel.
|
|
|
|
Here are some examples of how to apply these patches:
|
|
|
|
# moving from 2.6.12 to 2.6.12-git1
|
|
$ cd ~/linux-2.6.12 # change to the kernel source dir
|
|
$ patch -p1 < ../patch-2.6.12-git1 # apply the 2.6.12-git1 patch
|
|
$ cd ..
|
|
$ mv linux-2.6.12 linux-2.6.12-git1 # rename the kernel source dir
|
|
|
|
# moving from 2.6.12-git1 to 2.6.13-rc2-git3
|
|
$ cd ~/linux-2.6.12-git1 # change to the kernel source dir
|
|
$ patch -p1 -R < ../patch-2.6.12-git1 # revert the 2.6.12-git1 patch
|
|
# we now have a 2.6.12 kernel
|
|
$ patch -p1 < ../patch-2.6.13-rc2 # apply the 2.6.13-rc2 patch
|
|
# the kernel is now 2.6.13-rc2
|
|
$ patch -p1 < ../patch-2.6.13-rc2-git3 # apply the 2.6.13-rc2-git3 patch
|
|
# the kernel is now 2.6.13-rc2-git3
|
|
$ cd ..
|
|
$ mv linux-2.6.12-git1 linux-2.6.13-rc2-git3 # rename source dir
|
|
|
|
|
|
The -mm kernels
|
|
---
|
|
These are experimental kernels released by Andrew Morton.
|
|
|
|
The -mm tree serves as a sort of proving ground for new features and other
|
|
experimental patches.
|
|
Once a patch has proved its worth in -mm for a while Andrew pushes it on to
|
|
Linus for inclusion in mainline.
|
|
|
|
Although it's encouraged that patches flow to Linus via the -mm tree, this
|
|
is not always enforced.
|
|
Subsystem maintainers (or individuals) sometimes push their patches directly
|
|
to Linus, even though (or after) they have been merged and tested in -mm (or
|
|
sometimes even without prior testing in -mm).
|
|
|
|
You should generally strive to get your patches into mainline via -mm to
|
|
ensure maximum testing.
|
|
|
|
This branch is in constant flux and contains many experimental features, a
|
|
lot of debugging patches not appropriate for mainline etc and is the most
|
|
experimental of the branches described in this document.
|
|
|
|
These kernels are not appropriate for use on systems that are supposed to be
|
|
stable and they are more risky to run than any of the other branches (make
|
|
sure you have up-to-date backups - that goes for any experimental kernel but
|
|
even more so for -mm kernels).
|
|
|
|
These kernels in addition to all the other experimental patches they contain
|
|
usually also contain any changes in the mainline -git kernels available at
|
|
the time of release.
|
|
|
|
Testing of -mm kernels is greatly appreciated since the whole point of the
|
|
tree is to weed out regressions, crashes, data corruption bugs, build
|
|
breakage (and any other bug in general) before changes are merged into the
|
|
more stable mainline Linus tree.
|
|
But testers of -mm should be aware that breakage in this tree is more common
|
|
than in any other tree.
|
|
|
|
The -mm kernels are not released on a fixed schedule, but usually a few -mm
|
|
kernels are released in between each -rc kernel (1 to 3 is common).
|
|
The -mm kernels apply to either a base 2.6.x kernel (when no -rc kernels
|
|
have been released yet) or to a Linus -rc kernel.
|
|
|
|
Here are some examples of applying the -mm patches:
|
|
|
|
# moving from 2.6.12 to 2.6.12-mm1
|
|
$ cd ~/linux-2.6.12 # change to the 2.6.12 source dir
|
|
$ patch -p1 < ../2.6.12-mm1 # apply the 2.6.12-mm1 patch
|
|
$ cd ..
|
|
$ mv linux-2.6.12 linux-2.6.12-mm1 # rename the source appropriately
|
|
|
|
# moving from 2.6.12-mm1 to 2.6.13-rc3-mm3
|
|
$ cd ~/linux-2.6.12-mm1
|
|
$ patch -p1 -R < ../2.6.12-mm1 # revert the 2.6.12-mm1 patch
|
|
# we now have a 2.6.12 source
|
|
$ patch -p1 < ../patch-2.6.13-rc3 # apply the 2.6.13-rc3 patch
|
|
# we now have a 2.6.13-rc3 source
|
|
$ patch -p1 < ../2.6.13-rc3-mm3 # apply the 2.6.13-rc3-mm3 patch
|
|
$ cd ..
|
|
$ mv linux-2.6.12-mm1 linux-2.6.13-rc3-mm3 # rename the source dir
|
|
|
|
|
|
This concludes this list of explanations of the various kernel trees.
|
|
I hope you are now clear on how to apply the various patches and help testing
|
|
the kernel.
|
|
|
|
Thank you's to Randy Dunlap, Rolf Eike Beer, Linus Torvalds, Bodo Eggert,
|
|
Johannes Stezenbach, Grant Coady, Pavel Machek and others that I may have
|
|
forgotten for their reviews and contributions to this document.
|
|
|