Documentation/applying-patches.txt: Update the information there

This document is old: it is from Kernel v2.6.12 days.
Update it to the current status, and add a reference for the
linux-next tree.
Signed-off-by: NMauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: NJonathan Corbet <corbet@lwn.net>

Documentation/applying-patches.txt

@@ -6,7 +6,7 @@ Original by:
 	Jesper Juhl, August 2005
 
 Last update:
-	2006-01-05
+	2016-09-14
 
 
 A frequently asked question on the Linux Kernel Mailing List is how to apply
@@ -90,23 +90,23 @@ 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
+If your patch file is compressed with gzip or xz 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
+	xzcat path/to/patch-x.y.z.xz | patch -p1
+	bzcat path/to/patch-x.y.z.gz | 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 or xz on the file -- like this:
 
 ::
 
 	gunzip patch-x.y.z.gz
-	bunzip2 patch-x.y.z.bz2
+	xz -d patch-x.y.z.xz
 
 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.
@@ -226,16 +226,16 @@ 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
+This will let you move from something like 4.7.2 to 4.7.3 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:
+Here's how you'd go from 4.7.2 to 4.7.3 in a single step:
 
 ::
 
-	interdiff -z ../patch-2.6.12.2.bz2 ../patch-2.6.12.3.gz | patch -p1
+	interdiff -z ../patch-4.7.2.gz ../patch-4.7.3.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.
@@ -257,21 +257,13 @@ 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
+The 4.x.y (-stable) and 4.x patches live at
 
-	ftp://ftp.kernel.org/pub/linux/kernel/v2.6/
+	ftp://ftp.kernel.org/pub/linux/kernel/v4.x/
 
 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/
+	ftp://ftp.kernel.org/pub/linux/kernel/v4.x/testing/
 
 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
@@ -280,53 +272,55 @@ less bandwidth used globally and less load on the main kernel.org servers --
 these are good things, so do use mirrors when possible.
 
 
-The 2.6.x kernels
-=================
+The 4.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
+will be released (see below) on top of this base. Once a new 4.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.
+previous 4.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).
+To apply a patch moving from 4.6 to 4.7, you'd do the following (note
+that such patches do **NOT** apply on top of 4.x.y kernels but on top of the
+base 4.x kernel -- if you need to move from 4.x.y to 4.x+1 you need to
+first revert the 4.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
+	# moving from 4.6 to 4.7
+
+	$ cd ~/linux-4.6		# change to kernel source dir
+	$ patch -p1 < ../patch-4.7	# apply the 4.7 patch
 	$ cd ..
-	$ mv linux-2.6.11 linux-2.6.12		# rename source dir
+	$ mv linux-4.6 linux-4.7	# 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
+	# moving from 4.6.1 to 4.7
+
+	$ cd ~/linux-4.6.1		# change to kernel source dir
+	$ patch -p1 -R < ../patch-4.6.1	# revert the 4.6.1 patch
+					# source dir is now 4.6
+	$ patch -p1 < ../patch-4.7	# apply new 4.7 patch
 	$ cd ..
-	$ mv linux-2.6.11.1 linux-2.6.12	# rename source dir
+	$ mv linux-4.6.1 linux-4.7	# rename source dir
 
 
-The 2.6.x.y kernels
-===================
+The 4.x.y kernels
+=================
 
-Kernels with 4-digit versions are -stable kernels. They contain small(ish)
+Kernels with 3-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.
+in a given 4.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
+If no 4.x.y kernel is available, then the highest numbered 4.x kernel is
 the current stable kernel.
 
 .. note::
@@ -334,25 +328,25 @@ the current stable kernel.
  The -stable team usually do make incremental patches available as well
  as patches against the latest mainline release, but I only cover the
  non-incremental ones below. The incremental ones can be found at
- ftp://ftp.kernel.org/pub/linux/kernel/v2.6/incr/
+ ftp://ftp.kernel.org/pub/linux/kernel/v4.x/incr/
 
-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.
+These patches are not incremental, meaning that for example the 4.7.3
+patch does not apply on top of the 4.7.2 kernel source, but rather on top
+of the base 4.7 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.
+So, in order to apply the 4.7.3 patch to your existing 4.7.2 kernel
+source you have to first back out the 4.7.2 patch (so you are left with a
+base 4.7 kernel source) and then apply the new 4.7.3 patch.
 
 Here's a small example:
 
 ::
 
-	$ cd ~/linux-2.6.12.2			# change to 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 ~/linux-4.7.2		# change to the kernel source dir
+	$ patch -p1 -R < ../patch-4.7.2	# revert the 4.7.2 patch
+	$ patch -p1 < ../patch-4.7.3	# apply the new 4.7.3 patch
 	$ cd ..
-	$ mv linux-2.6.12.2 linux-2.6.12.3	# rename the kernel source dir
+	$ mv linux-4.7.2 linux-4.7.3	# rename the kernel source dir
 
 The -rc kernels
 ===============
@@ -371,37 +365,40 @@ 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
+The -rc patches are not incremental, they apply to a base 4.x kernel, just
+like the 4.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.
+So, 4.8-rc5 means that this is the fifth release candidate for the 4.8
+kernel and the patch should be applied on top of the 4.7 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 to the 2.6.12 source dir
-	$ patch -p1 < ../patch-2.6.13-rc3	# apply the 2.6.13-rc3 patch
+	# first an example of moving from 4.7 to 4.8-rc3
+
+	$ cd ~/linux-4.7			# change to the 4.7 source dir
+	$ patch -p1 < ../patch-4.8-rc3		# apply the 4.8-rc3 patch
 	$ cd ..
-	$ mv linux-2.6.12 linux-2.6.13-rc3	# rename the source dir
+	$ mv linux-4.7 linux-4.8-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 to 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
+	# now let's move from 4.8-rc3 to 4.8-rc5
+
+	$ cd ~/linux-4.8-rc3			# change to the 4.8-rc3 dir
+	$ patch -p1 -R < ../patch-4.8-rc3	# revert the 4.8-rc3 patch
+	$ patch -p1 < ../patch-4.8-rc5		# apply the new 4.8-rc5 patch
 	$ cd ..
-	$ mv linux-2.6.13-rc3 linux-2.6.13-rc5	# rename the source dir
+	$ mv linux-4.8-rc3 linux-4.8-rc5	# rename the source dir
+
+	# finally let's try and move from 4.7.3 to 4.8-rc5
 
-	# 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 ~/linux-4.7.3			# change to the kernel source dir
+	$ patch -p1 -R < ../patch-4.7.3		# revert the 4.7.3 patch
+	$ patch -p1 < ../patch-4.8-rc5		# apply new 4.8-rc5 patch
 	$ cd ..
-	$ mv linux-2.6.12.3 linux-2.6.13-rc5	# rename the kernel source dir
+	$ mv linux-4.7.3 linux-4.8-rc5		# rename the kernel source dir
 
 
 The -git kernels
@@ -415,100 +412,68 @@ Linus's 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.
+-git patches are not incremental and apply either to a base 4.x kernel or
+a base 4.x-rc kernel -- you can see which from their name.
+A patch named 4.7-git1 applies to the 4.7 kernel source and a patch
+named 4.8-rc3-git2 applies to the source of the 4.8-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
+	# moving from 4.7 to 4.7-git1
 
+	$ cd ~/linux-4.7			# change to the kernel source dir
+	$ patch -p1 < ../patch-4.7-git1		# apply the 4.7-git1 patch
+	$ cd ..
+	$ mv linux-4.7 linux-4.7-git1		# rename the kernel source dir
 
-The -mm kernels
-===============
+	# moving from 4.7-git1 to 4.8-rc2-git3
 
-These are experimental kernels released by Andrew Morton.
+	$ cd ~/linux-4.7-git1			# change to the kernel source dir
+	$ patch -p1 -R < ../patch-4.7-git1	# revert the 4.7-git1 patch
+						# we now have a 4.7 kernel
+	$ patch -p1 < ../patch-4.8-rc2		# apply the 4.8-rc2 patch
+						# the kernel is now 4.8-rc2
+	$ patch -p1 < ../patch-4.8-rc2-git3	# apply the 4.8-rc2-git3 patch
+						# the kernel is now 4.8-rc2-git3
+	$ cd ..
+	$ mv linux-4.7-git1 linux-4.8-rc2-git3	# rename source dir
 
-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.
+The -mm patches and the linux-next tree
+=======================================
 
-Although it's encouraged that patches flow to Linus via the -mm tree, this
-is not always enforced.
+The -mm patches are experimental patches released by Andrew Morton.
 
-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).
+In the past, -mm tree were used to also test subsystem patches, but this
+function is now done via the
+:ref:`linux-next <https://www.kernel.org/doc/man-pages/linux-next.html>`
+tree. The Subsystem maintainers push their patches first to linux-next,
+and, during the merge window, sends them directly to Linus.
 
-You should generally strive to get your patches into mainline via -mm to
-ensure maximum testing.
+The -mm patches serve as a sort of proving ground for new features and other
+experimental patches that aren't merged via a subsystem tree.
+Once such patches 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
+The linux-next tree is daily updated, and includes the -mm patches.
+Both are 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
+These patches 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.
+even more so for -mm patches or using a Kernel from the linux-next 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).
+Testing of -mm patches and linux-next is greatly appreciated since the whole
+point of those are 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.
 
-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
+But testers of -mm and linux-next should be aware that breakages are
+more common than in any other tree.
 
 
 This concludes this list of explanations of the various kernel trees.