Documentation - how to apply patches for various trees

Jesper Juhl

unread,

Aug 2, 2005, 5:50:20 PM8/2/05

to

Hi,

How to apply the -rc, -git, -mm and the 2.6.x.y (-stable) patches is a quite
frequently asked question on LKML and elsewhere.
Since so many people seem to be confused by this I gathered it ought to be
properly documented once and for all so we a) get more people testing those
trees and b) get asked this question less often.
So, I sat down and wrote such a document.

Below is a patch to add a new file "applying-patches.txt" to Documentation/
This document describes each of the trees and gives examples on how to apply
the various patches.

Looking forward to your feedback (and possible inclusion).

I guess this document could also be placed somewhere on kernel.org and linked
to from the front page so that people downloading the various patches will
have this information available at their fingertips.

Signed-off-by: Jesper Juhl <jespe...@gmail.com>
---

Documentation/applying-patches.txt | 221 +++++++++++++++++++++++++++++++++++++
1 files changed, 221 insertions(+)

diff -uP linux-2.6.13-rc5-orig/Documentation/applying-patches.txt linux-2.6.13-rc5/Documentation/applying-patches.txt
--- linux-2.6.13-rc5-orig/Documentation/applying-patches.txt 1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.13-rc5/Documentation/applying-patches.txt 2005-08-02 23:17:13.000000000 +0200
@@ -0,0 +1,221 @@
+
+ Applying Patches To The Linux Kernel
+ ------------------------------------
+
+ (Written by Jesper Juhl, August 2005)
+
+
+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.
+
+
+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.
+
+
+How do I apply 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 releative 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 dirs it was generated
+against - 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.
+
+
+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/
+
+
+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 to 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).
+
+# 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 inux-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 interrested 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 ReleaseCandidate kernels. These are development kernels released
+by Linus whenever he deems the current git (the kernels source management
+tool) tree to be in a resonably 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 kernel 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 and have not been looked over and deemed worthy of
+-rc status yet. -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. 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 a 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 and I
+hope you are now crystal clear on how to apply the various patches and help
+testing the kernel.

-
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Randy.Dunlap

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Aug 2, 2005, 6:50:08 PM8/2/05

to

On Tue, 2 Aug 2005, Jesper Juhl wrote:

> Hi,

+These should both be present in the patch file metadata.

> +
> +
> +How do I apply 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 releative to the parent directory

relative

> +holding the kernel source dir. This means that paths to files inside the
> +patch file contain the name of the kernel source dirs it was generated

directories

> +against - 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.
> +
> +
> +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/

or ftp.cc.kernel.org, where cc is a country code.

> +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/
> +
> +
> +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 to of this base.

top

interested

> +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 ReleaseCandidate kernels. These are development kernels released

"release-candidate" ?

> +by Linus whenever he deems the current git (the kernels source management

kernel's

> +tool) tree to be in a resonably sane state adequate for testing. These

reasonably

> +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 kernel but do not want to run some of the really experimental

kernels

I think that this implies a little too much for -rc's regarding their
review and readiness.

or other subsystem maintainers push their own patches to Linus, even
though (or after) they have been merged and tested in -mm.

> +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 a more risky to run than any

are

> +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

-mm

> +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 and I
> +hope you are now crystal clear on how to apply the various patches and help
> +testing the kernel.
> -

--
~Randy

Richard Hubbell

unread,

Aug 2, 2005, 9:10:09 PM8/2/05

to

Thank you! I agree that having a link off of kernel.org makes sense.

Richard

Puneet Vyas

unread,

Aug 2, 2005, 10:10:07 PM8/2/05

to

Thanks for this wonderful effort! Add one more to the testing team.

~Puneet

Jesper Juhl wrote:

>Hi,
>
>How to apply the -rc, -git, -mm and the 2.6.x.y (-stable) patches is a quite
>frequently asked question on LKML and elsewhere.
>Since so many people seem to be confused by this I gathered it ought to be
>properly documented once and for all so we a) get more people testing those
>trees and b) get asked this question less often.
>So, I sat down and wrote such a document.
>
>

-

Rolf Eike Beer

unread,

Aug 3, 2005, 2:40:16 AM8/3/05

to

Jesper Juhl wrote:

>+Where can I download the patches?

Maybe it would be useful to once again mention that local mirrors should be
used at least for stable releases and */testing/*.

>+The 2.6.x kernels
[...]

>+# 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

patch also nows "-i": patch -p1 -i ../patch-2.6.12

More likely the user will get the patch compressed either with bzip2 or gzip,
so I think it would be useful to tell once more how to apply such a patch:

bzcat ../patch-2.6.12.bz2 | patch -p1

>+The 2.6.x.y kernels

>+$ 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 better way would probably be to use interdiff. Another goodie is that
interdiff knows about -z:

cd ~/linux-2.6.12.2
interdiff -z ../patch-2.6.12.2.bz2 ../patch-2.6.12.3.gz | patch -p1

This should only be shown as "another way" to do so. Sometimes interdiff get's
confused and breaks things, although this is very unlikely for the stable
diffs.

>+The -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.

These two "contain"'s that close to each user are likely to confuse. In a
German text I would but a comma before "in addition" and behind the first
"contain", don't know what the rules for this are in English.

Eike

Randy.Dunlap

unread,

Aug 3, 2005, 10:50:08 AM8/3/05

to

Another (better IMO) solution is to use 'ketchup'.
It knows about all of these revisions/patches and how to download
and apply them AFAIK.
http://www.selenic.com/ketchup/

> >+The -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.
>
> These two "contain"'s that close to each user are likely to confuse. In a
> German text I would but a comma before "in addition" and behind the first
> "contain", don't know what the rules for this are in English.
>
> Eike

--
~Randy

Linus Torvalds

unread,

Aug 3, 2005, 5:20:10 PM8/3/05

to

On Wed, 3 Aug 2005, Jesper Juhl wrote:
>
> Here's an updated version of my document that attempts to give a short
> explanation of the various kernel trees and how to apply their patches.
> It incorporates all the feedback I've gotten (thanks guys).

Can we have more whitespace?

You either have very long paragraphs, or no whitespace between them: I
can't quite decide which one.

So leave an empty line between paragraphs (and if you already do, you need
to split them ;) because it's very tiring to not have a nice break every
once in the flow of text.

Long paragraphs may be acceptable in fictional literary work that you read
without thinking about what you're reading. There you get into the "flow"
of the text, and you hopefully don't need to have very many visual breaks
to keep as acnhor-points. However, the same is certainly not true in
technical text, especially something like this where you're trying to
explain somethign that the recipient doesn't ncessarily know.

My rule of thumb is that if you don't have a new paragraph roughly every
five or six lines, it's likely problematic. Maybe I have a shorter
attention span than most, but I don't think so - I just find it much
easier to read text that is nicely broken up, and when it's a "pure ASCII"
medium the only break that works well is an empty line (possibly with
indentation for further visual help - although in this context indentation
tends to be used for a separate issue: examples etc, and is not good for
paragraphs).

And since we have a single empty line implying paragraph breaks, feel free
to use multiple empty lines to imply "bigger" breaks (you seem to do this
already).

This email was written with an average paragraph length of 4 lines.

Linus

Jesper Juhl

unread,

Aug 3, 2005, 5:30:19 PM8/3/05

to

On Wednesday 03 August 2005 23:08, Linus Torvalds wrote:
>
> On Wed, 3 Aug 2005, Jesper Juhl wrote:
> >
> > Here's an updated version of my document that attempts to give a short
> > explanation of the various kernel trees and how to apply their patches.
> > It incorporates all the feedback I've gotten (thanks guys).
>
> Can we have more whitespace?
>

Certainly.

> And since we have a single empty line implying paragraph breaks, feel free
> to use multiple empty lines to imply "bigger" breaks (you seem to do this
> already).
>

Here's an updated version with more whitespace.

Signed-off-by: Jesper Juhl <jespe...@gmail.com>
---

Documentation/applying-patches.txt | 323 +++++++++++++++++++++++++++++++++++++
1 files changed, 323 insertions(+)

diff -uP linux-2.6.13-rc5-orig/Documentation/applying-patches.txt linux-2.6.13-rc5/Documentation/applying-patches.txt
--- linux-2.6.13-rc5-orig/Documentation/applying-patches.txt 1970-01-01 01:00:00.000000000 +0100

+++ linux-2.6.13-rc5/Documentation/applying-patches.txt 2005-08-03 23:23:24.000000000 +0200
@@ -0,0 +1,323 @@

+
+ Applying Patches To The Linux Kernel
+ ------------------------------------
+
+ (Written by Jesper Juhl, August 2005)
+
+
+
+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.
+
+
+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.

+
+
+How do I apply 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.
+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.
+
+
+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
+
+but 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.
+
+
+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
+uncompression.
+
+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 adviced 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/).

+
+
+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 bandwith 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 inux-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.
+

+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

+
+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 and I
+hope you are now crystal clear on how to apply the various patches and help
+testing the kernel.

+

Bodo Eggert

unread,

Aug 3, 2005, 5:50:07 PM8/3/05

to

On Wed, 3 Aug 2005, Jesper Juhl wrote:

> +What is a patch?

> +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.

This is usurally not true for kernel patches, the directories are mostly
named a and b. You can however deduce the to-bepatched version and the
patched version from the filename.

> +How do I apply 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 - 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)

Same issue.

> 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.

> +How do I feed a patch/diff file to `patch'?

[...]

Or: bzcat patch1 patch2 patch3 | (cd linux-oldversion && patch -p1)

Finding out if a patch applied correctly
---
A quick check is to search for .rej files. Unfortunately some errors

How do I undo a patch?
---
You can undo a patch by supplying the -R switch to patch. If you patched
using zcat ../patch.gz | patch -p1, zcat ../patch.gz | patch -Rp1 will
undo the changes as long as the patch applied correctly.

Common errors while patching
---
"File to patch:"

Patch could not find a file to be patched. Most probably you forgot to
use -p1 or you're in the wrong directory. Less often, you'll find
patches that need to be applied with -p0 instead (you can't just omit
-p0!). ^^^^^^^^^^^^^^^^^^^
^^^^^ [IIRC]

Sometimes this is the result of an incomplete tarball, a out-of-space
error while unpacking or a fsck.

"Hunk #2 succeeded at 1887 with fuzz 2 (offset 7 lines)."

The patch was applied, but it might be applied to the wrong place
because you patched the "wrong" source. The result might not work
correctly.

"Hunk #3 FAILED at 2387."

The patch could not be applied correctly. This is usurally fatal, except
if you apply external patches to the stable series (e.g. to 2.6.23.42
instead of 2.6.23) and the reject is in the toplevel Makefile.
(You'll have to manually edit the Makefile and change the version string
as recorded in Makefile.rej)

If you apply more than one external patch, the same thing will happen,
but there is no guarantee for a working kernel (the changes may bite
each other).

You can most likely recover the source tree by undoing the patch and
removing the .rej and .orig files. YMMV.

"Reversed (or previously applied) patch detected! Assume -R? [n]"

Either you really applied the patch before, or the patch is for some
other source. If this is not the very first message, the source is
most likely unusable by now.

"patch: **** unexpected end of file in patch"
Your download is broken. Re-get the file.

--
To steal information from a person is called plagiarism. To steal
information from the enemy is called gathering intelligence.

Jesper Juhl

unread,

Aug 3, 2005, 7:30:13 PM8/3/05

to

On Wednesday 03 August 2005 23:46, Bodo Eggert wrote:
> On Wed, 3 Aug 2005, Jesper Juhl wrote:
>
> > +What is a patch?
>
> > +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.
>
> This is usurally not true for kernel patches, the directories are mostly
> named a and b. You can however deduce the to-bepatched version and the
> patched version from the filename.
>

hmm, I'd say the patch filename could be considered "metadata" as well.

> [...]
>
> Or: bzcat patch1 patch2 patch3 | (cd linux-oldversion && patch -p1)
>

yes, there are many ways, impossible to list them all, but this might be a
good example to add, just to show application of several patches in one go.

>
<snip lots of good stuff>

I need to get some sleep now, but I'll add most of your text to the document
tomorrow and post a new patch.

Thanks!

--
Jesper

Johannes Stezenbach

unread,

Aug 3, 2005, 8:00:14 PM8/3/05

to

On Wed, Aug 03, 2005 Jesper Juhl wrote:
> +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

I think you should mention the -s flag. Given the size of an
average kernel patch it is otherwise very likely that errors scroll
away unnoticed.

OTOH you might also want to add a mention of lsdiff and diffstat.

Johannes

Grant Coady

unread,

Aug 3, 2005, 8:40:10 PM8/3/05

to

Hi Jesper,
On Wed, 3 Aug 2005 23:28:06 +0200, Jesper Juhl <jespe...@gmail.com> wrote:

I like it, just a little concerned about confusing new user with too
many alternative patching methods up front...

>+ 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
>+
>+but 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:

cat path/to/patch-x.y.z.gz | patch -p1

>+ zcat path/to/patch-x.y.z.gz | patch -p1
>+ bzcat path/to/patch-x.y.z.bz2 | patch -p1

In a howto, I'd prefer _one_ consistent method to reduce the
reader's confusion.

The above trio of commands serves me well over many years' kernel
patching, and it is trivial to up-arrow, home, change compression
method, retry ... when my fingers get ahead of my mind :)

Experience users recognise the intent of the commands and use their
favourite method instead, almost without thinking.

Spelling:

s/uncompression/decompression/
s/adviced/advised/
s/bandwith/bandwidth/

Cheers,
Grant.

Rolf Eike Beer

unread,

Aug 4, 2005, 3:50:09 AM8/4/05

to

Jesper Juhl wrote:
>+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/

^

To be consistent you must add a space here.

Eike

Pavel Machek

unread,

Aug 4, 2005, 4:30:18 PM8/4/05

to

Hi!

> How to apply the -rc, -git, -mm and the 2.6.x.y (-stable) patches is a quite
> frequently asked question on LKML and elsewhere.
> Since so many people seem to be confused by this I gathered it ought to be
> properly documented once and for all so we a) get more people testing those
> trees and b) get asked this question less often.
> So, I sat down and wrote such a document.
>
> Below is a patch to add a new file "applying-patches.txt" to Documentation/
> This document describes each of the trees and gives examples on how to apply
> the various patches.
>
> Looking forward to your feedback (and possible inclusion).
>
> I guess this document could also be placed somewhere on kernel.org and linked
> to from the front page so that people downloading the various patches will
> have this information available at their fingertips.

Perhaps including ketchup in linux/scripts makes sense? Places for
download slowly change so it needs to be kept up-to-date, and it is
*very* nice to use...

Pavel

--
teflon -- maybe it is a trademark, but it should not be.

Jesper Juhl

unread,

Aug 5, 2005, 7:00:14 PM8/5/05

to

On Wednesday 03 August 2005 23:08, Linus Torvalds wrote:
>
> On Wed, 3 Aug 2005, Jesper Juhl wrote:
> >
> > Here's an updated version of my document that attempts to give a short
> > explanation of the various kernel trees and how to apply their patches.
> > It incorporates all the feedback I've gotten (thanks guys).
>
> Can we have more whitespace?
>

[snip]

The new version of the document below has more whitespace and also
incorporates a lot of feedback I've gotten since the last version I posted.

I think this is getting close to the point where it could be included.
What do you say?

Add a new document describing the major kernel trees and how to apply their patches.

Signed-off-by: Jesper Juhl <jespe...@gmail.com>
---

Documentation/applying-patches.txt | 439 +++++++++++++++++++++++++++++++++++++
1 files changed, 439 insertions(+)

diff -uP linux-2.6.13-rc5-orig/Documentation/applying-patches.txt linux-2.6.13-rc5/Documentation/applying-patches.txt
--- linux-2.6.13-rc5-orig/Documentation/applying-patches.txt 1970-01-01 01:00:00.000000000 +0100

+++ linux-2.6.13-rc5/Documentation/applying-patches.txt 2005-08-06 00:46:17.000000000 +0200
@@ -0,0 +1,439 @@

+
+ Applying Patches To The Linux Kernel
+ ------------------------------------
+
+ (Written by Jesper Juhl, August 2005)
+
+
+
+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 exactely 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
+redownloading 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.