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609d99a3 | 1 | .. _applying_patches: |
754c7976 | 2 | |
9299c3e9 MCC |
3 | Applying Patches To The Linux Kernel |
4 | ++++++++++++++++++++++++++++++++++++ | |
754c7976 | 5 | |
9299c3e9 MCC |
6 | Original by: |
7 | Jesper Juhl, August 2005 | |
8 | ||
9 | Last update: | |
330ae7e9 | 10 | 2016-09-14 |
754c7976 JJ |
11 | |
12 | ||
13 | A frequently asked question on the Linux Kernel Mailing List is how to apply | |
14 | a patch to the kernel or, more specifically, what base kernel a patch for | |
15 | one of the many trees/branches should be applied to. Hopefully this document | |
16 | will explain this to you. | |
17 | ||
18 | In addition to explaining how to apply and revert patches, a brief | |
19 | description of the different kernel trees (and examples of how to apply | |
20 | their specific patches) is also provided. | |
21 | ||
22 | ||
23 | What is a patch? | |
9299c3e9 MCC |
24 | ================ |
25 | ||
26 | A patch is a small text document containing a delta of changes between two | |
27 | different versions of a source tree. Patches are created with the ``diff`` | |
754c7976 | 28 | program. |
9299c3e9 | 29 | |
754c7976 JJ |
30 | To correctly apply a patch you need to know what base it was generated from |
31 | and what new version the patch will change the source tree into. These | |
32 | should both be present in the patch file metadata or be possible to deduce | |
33 | from the filename. | |
34 | ||
35 | ||
36 | How do I apply or revert a patch? | |
9299c3e9 MCC |
37 | ================================= |
38 | ||
39 | You apply a patch with the ``patch`` program. The patch program reads a diff | |
754c7976 JJ |
40 | (or patch) file and makes the changes to the source tree described in it. |
41 | ||
42 | Patches for the Linux kernel are generated relative to the parent directory | |
43 | holding the kernel source dir. | |
44 | ||
45 | This means that paths to files inside the patch file contain the name of the | |
46 | kernel source directories it was generated against (or some other directory | |
47 | names like "a/" and "b/"). | |
9299c3e9 | 48 | |
754c7976 JJ |
49 | Since this is unlikely to match the name of the kernel source dir on your |
50 | local machine (but is often useful info to see what version an otherwise | |
51 | unlabeled patch was generated against) you should change into your kernel | |
52 | source directory and then strip the first element of the path from filenames | |
9299c3e9 MCC |
53 | in the patch file when applying it (the ``-p1`` argument to ``patch`` does |
54 | this). | |
754c7976 JJ |
55 | |
56 | To revert a previously applied patch, use the -R argument to patch. | |
57 | So, if you applied a patch like this: | |
9299c3e9 MCC |
58 | |
59 | :: | |
60 | ||
754c7976 JJ |
61 | patch -p1 < ../patch-x.y.z |
62 | ||
63 | You can revert (undo) it like this: | |
9299c3e9 MCC |
64 | |
65 | :: | |
66 | ||
754c7976 JJ |
67 | patch -R -p1 < ../patch-x.y.z |
68 | ||
69 | ||
9299c3e9 MCC |
70 | How do I feed a patch/diff file to ``patch``? |
71 | ============================================= | |
72 | ||
73 | This (as usual with Linux and other UNIX like operating systems) can be | |
754c7976 | 74 | done in several different ways. |
9299c3e9 | 75 | |
754c7976 JJ |
76 | In all the examples below I feed the file (in uncompressed form) to patch |
77 | via stdin using the following syntax: | |
9299c3e9 MCC |
78 | |
79 | :: | |
80 | ||
754c7976 JJ |
81 | patch -p1 < path/to/patch-x.y.z |
82 | ||
83 | If you just want to be able to follow the examples below and don't want to | |
84 | know of more than one way to use patch, then you can stop reading this | |
85 | section here. | |
86 | ||
87 | Patch can also get the name of the file to use via the -i argument, like | |
88 | this: | |
9299c3e9 MCC |
89 | |
90 | :: | |
91 | ||
754c7976 JJ |
92 | patch -p1 -i path/to/patch-x.y.z |
93 | ||
330ae7e9 | 94 | If your patch file is compressed with gzip or xz and you don't want to |
754c7976 JJ |
95 | uncompress it before applying it, then you can feed it to patch like this |
96 | instead: | |
9299c3e9 MCC |
97 | |
98 | :: | |
99 | ||
330ae7e9 MCC |
100 | xzcat path/to/patch-x.y.z.xz | patch -p1 |
101 | bzcat path/to/patch-x.y.z.gz | patch -p1 | |
754c7976 JJ |
102 | |
103 | If you wish to uncompress the patch file by hand first before applying it | |
104 | (what I assume you've done in the examples below), then you simply run | |
330ae7e9 | 105 | gunzip or xz on the file -- like this: |
9299c3e9 MCC |
106 | |
107 | :: | |
108 | ||
754c7976 | 109 | gunzip patch-x.y.z.gz |
330ae7e9 | 110 | xz -d patch-x.y.z.xz |
754c7976 JJ |
111 | |
112 | Which will leave you with a plain text patch-x.y.z file that you can feed to | |
9299c3e9 | 113 | patch via stdin or the ``-i`` argument, as you prefer. |
754c7976 | 114 | |
9299c3e9 | 115 | A few other nice arguments for patch are ``-s`` which causes patch to be silent |
754c7976 | 116 | except for errors which is nice to prevent errors from scrolling out of the |
9299c3e9 MCC |
117 | screen too fast, and ``--dry-run`` which causes patch to just print a listing of |
118 | what would happen, but doesn't actually make any changes. Finally ``--verbose`` | |
754c7976 JJ |
119 | tells patch to print more information about the work being done. |
120 | ||
121 | ||
122 | Common errors when patching | |
9299c3e9 MCC |
123 | =========================== |
124 | ||
125 | When patch applies a patch file it attempts to verify the sanity of the | |
754c7976 | 126 | file in different ways. |
9299c3e9 | 127 | |
2d69049a | 128 | Checking that the file looks like a valid patch file and checking the code |
754c7976 JJ |
129 | around the bits being modified matches the context provided in the patch are |
130 | just two of the basic sanity checks patch does. | |
131 | ||
132 | If patch encounters something that doesn't look quite right it has two | |
133 | options. It can either refuse to apply the changes and abort or it can try | |
134 | to find a way to make the patch apply with a few minor changes. | |
135 | ||
136 | One example of something that's not 'quite right' that patch will attempt to | |
137 | fix up is if all the context matches, the lines being changed match, but the | |
138 | line numbers are different. This can happen, for example, if the patch makes | |
139 | a change in the middle of the file but for some reasons a few lines have | |
140 | been added or removed near the beginning of the file. In that case | |
141 | everything looks good it has just moved up or down a bit, and patch will | |
142 | usually adjust the line numbers and apply the patch. | |
143 | ||
144 | Whenever patch applies a patch that it had to modify a bit to make it fit | |
9299c3e9 | 145 | it'll tell you about it by saying the patch applied with **fuzz**. |
754c7976 JJ |
146 | You should be wary of such changes since even though patch probably got it |
147 | right it doesn't /always/ get it right, and the result will sometimes be | |
148 | wrong. | |
149 | ||
150 | When patch encounters a change that it can't fix up with fuzz it rejects it | |
9299c3e9 | 151 | outright and leaves a file with a ``.rej`` extension (a reject file). You can |
90f2447d | 152 | read this file to see exactly what change couldn't be applied, so you can |
754c7976 JJ |
153 | go fix it up by hand if you wish. |
154 | ||
c594a50d | 155 | If you don't have any third-party patches applied to your kernel source, but |
754c7976 JJ |
156 | only patches from kernel.org and you apply the patches in the correct order, |
157 | and have made no modifications yourself to the source files, then you should | |
158 | never see a fuzz or reject message from patch. If you do see such messages | |
159 | anyway, then there's a high risk that either your local source tree or the | |
160 | patch file is corrupted in some way. In that case you should probably try | |
90f2447d | 161 | re-downloading the patch and if things are still not OK then you'd be advised |
754c7976 JJ |
162 | to start with a fresh tree downloaded in full from kernel.org. |
163 | ||
164 | Let's look a bit more at some of the messages patch can produce. | |
165 | ||
9299c3e9 | 166 | If patch stops and presents a ``File to patch:`` prompt, then patch could not |
754c7976 JJ |
167 | find a file to be patched. Most likely you forgot to specify -p1 or you are |
168 | in the wrong directory. Less often, you'll find patches that need to be | |
9299c3e9 | 169 | applied with ``-p0`` instead of ``-p1`` (reading the patch file should reveal if |
c594a50d | 170 | this is the case -- if so, then this is an error by the person who created |
754c7976 JJ |
171 | the patch but is not fatal). |
172 | ||
9299c3e9 | 173 | If you get ``Hunk #2 succeeded at 1887 with fuzz 2 (offset 7 lines).`` or a |
754c7976 JJ |
174 | message similar to that, then it means that patch had to adjust the location |
175 | of the change (in this example it needed to move 7 lines from where it | |
176 | expected to make the change to make it fit). | |
9299c3e9 | 177 | |
754c7976 JJ |
178 | The resulting file may or may not be OK, depending on the reason the file |
179 | was different than expected. | |
9299c3e9 | 180 | |
754c7976 JJ |
181 | This often happens if you try to apply a patch that was generated against a |
182 | different kernel version than the one you are trying to patch. | |
183 | ||
9299c3e9 | 184 | If you get a message like ``Hunk #3 FAILED at 2387.``, then it means that the |
754c7976 | 185 | patch could not be applied correctly and the patch program was unable to |
9299c3e9 MCC |
186 | fuzz its way through. This will generate a ``.rej`` file with the change that |
187 | caused the patch to fail and also a ``.orig`` file showing you the original | |
754c7976 JJ |
188 | content that couldn't be changed. |
189 | ||
9299c3e9 | 190 | If you get ``Reversed (or previously applied) patch detected! Assume -R? [n]`` |
754c7976 JJ |
191 | then patch detected that the change contained in the patch seems to have |
192 | already been made. | |
9299c3e9 | 193 | |
754c7976 JJ |
194 | If you actually did apply this patch previously and you just re-applied it |
195 | in error, then just say [n]o and abort this patch. If you applied this patch | |
196 | previously and actually intended to revert it, but forgot to specify -R, | |
9299c3e9 MCC |
197 | then you can say [**y**]es here to make patch revert it for you. |
198 | ||
754c7976 JJ |
199 | This can also happen if the creator of the patch reversed the source and |
200 | destination directories when creating the patch, and in that case reverting | |
201 | the patch will in fact apply it. | |
202 | ||
9299c3e9 MCC |
203 | A message similar to ``patch: **** unexpected end of file in patch`` or |
204 | ``patch unexpectedly ends in middle of line`` means that patch could make no | |
205 | sense of the file you fed to it. Either your download is broken, you tried to | |
206 | feed patch a compressed patch file without uncompressing it first, or the patch | |
c594a50d RD |
207 | file that you are using has been mangled by a mail client or mail transfer |
208 | agent along the way somewhere, e.g., by splitting a long line into two lines. | |
209 | Often these warnings can easily be fixed by joining (concatenating) the | |
210 | two lines that had been split. | |
754c7976 JJ |
211 | |
212 | As I already mentioned above, these errors should never happen if you apply | |
213 | a patch from kernel.org to the correct version of an unmodified source tree. | |
214 | So if you get these errors with kernel.org patches then you should probably | |
c594a50d | 215 | assume that either your patch file or your tree is broken and I'd advise you |
754c7976 JJ |
216 | to start over with a fresh download of a full kernel tree and the patch you |
217 | wish to apply. | |
218 | ||
219 | ||
9299c3e9 MCC |
220 | Are there any alternatives to ``patch``? |
221 | ======================================== | |
90f2447d | 222 | |
9299c3e9 MCC |
223 | |
224 | Yes there are alternatives. | |
225 | ||
226 | You can use the ``interdiff`` program (http://cyberelk.net/tim/patchutils/) to | |
90f2447d JJ |
227 | generate a patch representing the differences between two patches and then |
228 | apply the result. | |
9299c3e9 | 229 | |
330ae7e9 | 230 | This will let you move from something like 4.7.2 to 4.7.3 in a single |
754c7976 JJ |
231 | step. The -z flag to interdiff will even let you feed it patches in gzip or |
232 | bzip2 compressed form directly without the use of zcat or bzcat or manual | |
233 | decompression. | |
234 | ||
330ae7e9 | 235 | Here's how you'd go from 4.7.2 to 4.7.3 in a single step: |
9299c3e9 MCC |
236 | |
237 | :: | |
238 | ||
330ae7e9 | 239 | interdiff -z ../patch-4.7.2.gz ../patch-4.7.3.gz | patch -p1 |
754c7976 JJ |
240 | |
241 | Although interdiff may save you a step or two you are generally advised to | |
242 | do the additional steps since interdiff can get things wrong in some cases. | |
243 | ||
9299c3e9 | 244 | Another alternative is ``ketchup``, which is a python script for automatic |
754c7976 JJ |
245 | downloading and applying of patches (http://www.selenic.com/ketchup/). |
246 | ||
9299c3e9 | 247 | Other nice tools are diffstat, which shows a summary of changes made by a |
c594a50d RD |
248 | patch; lsdiff, which displays a short listing of affected files in a patch |
249 | file, along with (optionally) the line numbers of the start of each patch; | |
250 | and grepdiff, which displays a list of the files modified by a patch where | |
754c7976 JJ |
251 | the patch contains a given regular expression. |
252 | ||
253 | ||
254 | Where can I download the patches? | |
9299c3e9 MCC |
255 | ================================= |
256 | ||
257 | The patches are available at http://kernel.org/ | |
754c7976 JJ |
258 | Most recent patches are linked from the front page, but they also have |
259 | specific homes. | |
260 | ||
330ae7e9 | 261 | The 4.x.y (-stable) and 4.x patches live at |
9299c3e9 | 262 | |
330ae7e9 | 263 | ftp://ftp.kernel.org/pub/linux/kernel/v4.x/ |
754c7976 JJ |
264 | |
265 | The -rc patches live at | |
9299c3e9 | 266 | |
330ae7e9 | 267 | ftp://ftp.kernel.org/pub/linux/kernel/v4.x/testing/ |
9299c3e9 MCC |
268 | |
269 | In place of ``ftp.kernel.org`` you can use ``ftp.cc.kernel.org``, where cc is a | |
754c7976 JJ |
270 | country code. This way you'll be downloading from a mirror site that's most |
271 | likely geographically closer to you, resulting in faster downloads for you, | |
c594a50d RD |
272 | less bandwidth used globally and less load on the main kernel.org servers -- |
273 | these are good things, so do use mirrors when possible. | |
754c7976 JJ |
274 | |
275 | ||
330ae7e9 MCC |
276 | The 4.x kernels |
277 | =============== | |
9299c3e9 MCC |
278 | |
279 | These are the base stable releases released by Linus. The highest numbered | |
754c7976 JJ |
280 | release is the most recent. |
281 | ||
c594a50d | 282 | If regressions or other serious flaws are found, then a -stable fix patch |
330ae7e9 | 283 | will be released (see below) on top of this base. Once a new 4.x base |
754c7976 | 284 | kernel is released, a patch is made available that is a delta between the |
330ae7e9 | 285 | previous 4.x kernel and the new one. |
754c7976 | 286 | |
330ae7e9 MCC |
287 | To apply a patch moving from 4.6 to 4.7, you'd do the following (note |
288 | that such patches do **NOT** apply on top of 4.x.y kernels but on top of the | |
289 | base 4.x kernel -- if you need to move from 4.x.y to 4.x+1 you need to | |
290 | first revert the 4.x.y patch). | |
754c7976 JJ |
291 | |
292 | Here are some examples: | |
293 | ||
9299c3e9 MCC |
294 | :: |
295 | ||
330ae7e9 MCC |
296 | # moving from 4.6 to 4.7 |
297 | ||
298 | $ cd ~/linux-4.6 # change to kernel source dir | |
299 | $ patch -p1 < ../patch-4.7 # apply the 4.7 patch | |
9299c3e9 | 300 | $ cd .. |
330ae7e9 | 301 | $ mv linux-4.6 linux-4.7 # rename source dir |
754c7976 | 302 | |
330ae7e9 MCC |
303 | # moving from 4.6.1 to 4.7 |
304 | ||
305 | $ cd ~/linux-4.6.1 # change to kernel source dir | |
306 | $ patch -p1 -R < ../patch-4.6.1 # revert the 4.6.1 patch | |
307 | # source dir is now 4.6 | |
308 | $ patch -p1 < ../patch-4.7 # apply new 4.7 patch | |
9299c3e9 | 309 | $ cd .. |
330ae7e9 | 310 | $ mv linux-4.6.1 linux-4.7 # rename source dir |
754c7976 JJ |
311 | |
312 | ||
330ae7e9 MCC |
313 | The 4.x.y kernels |
314 | ================= | |
9299c3e9 | 315 | |
330ae7e9 | 316 | Kernels with 3-digit versions are -stable kernels. They contain small(ish) |
754c7976 | 317 | critical fixes for security problems or significant regressions discovered |
330ae7e9 | 318 | in a given 4.x kernel. |
754c7976 JJ |
319 | |
320 | This is the recommended branch for users who want the most recent stable | |
321 | kernel and are not interested in helping test development/experimental | |
322 | versions. | |
323 | ||
330ae7e9 | 324 | If no 4.x.y kernel is available, then the highest numbered 4.x kernel is |
754c7976 JJ |
325 | the current stable kernel. |
326 | ||
9299c3e9 MCC |
327 | .. note:: |
328 | ||
329 | The -stable team usually do make incremental patches available as well | |
c594a50d RD |
330 | as patches against the latest mainline release, but I only cover the |
331 | non-incremental ones below. The incremental ones can be found at | |
330ae7e9 | 332 | ftp://ftp.kernel.org/pub/linux/kernel/v4.x/incr/ |
c594a50d | 333 | |
330ae7e9 MCC |
334 | These patches are not incremental, meaning that for example the 4.7.3 |
335 | patch does not apply on top of the 4.7.2 kernel source, but rather on top | |
336 | of the base 4.7 kernel source. | |
9299c3e9 | 337 | |
330ae7e9 MCC |
338 | So, in order to apply the 4.7.3 patch to your existing 4.7.2 kernel |
339 | source you have to first back out the 4.7.2 patch (so you are left with a | |
340 | base 4.7 kernel source) and then apply the new 4.7.3 patch. | |
754c7976 JJ |
341 | |
342 | Here's a small example: | |
343 | ||
9299c3e9 | 344 | :: |
754c7976 | 345 | |
330ae7e9 MCC |
346 | $ cd ~/linux-4.7.2 # change to the kernel source dir |
347 | $ patch -p1 -R < ../patch-4.7.2 # revert the 4.7.2 patch | |
348 | $ patch -p1 < ../patch-4.7.3 # apply the new 4.7.3 patch | |
9299c3e9 | 349 | $ cd .. |
330ae7e9 | 350 | $ mv linux-4.7.2 linux-4.7.3 # rename the kernel source dir |
754c7976 JJ |
351 | |
352 | The -rc kernels | |
9299c3e9 MCC |
353 | =============== |
354 | ||
355 | These are release-candidate kernels. These are development kernels released | |
754c7976 JJ |
356 | by Linus whenever he deems the current git (the kernel's source management |
357 | tool) tree to be in a reasonably sane state adequate for testing. | |
358 | ||
359 | These kernels are not stable and you should expect occasional breakage if | |
360 | you intend to run them. This is however the most stable of the main | |
361 | development branches and is also what will eventually turn into the next | |
362 | stable kernel, so it is important that it be tested by as many people as | |
363 | possible. | |
364 | ||
365 | This is a good branch to run for people who want to help out testing | |
366 | development kernels but do not want to run some of the really experimental | |
367 | stuff (such people should see the sections about -git and -mm kernels below). | |
368 | ||
330ae7e9 MCC |
369 | The -rc patches are not incremental, they apply to a base 4.x kernel, just |
370 | like the 4.x.y patches described above. The kernel version before the -rcN | |
754c7976 JJ |
371 | suffix denotes the version of the kernel that this -rc kernel will eventually |
372 | turn into. | |
9299c3e9 | 373 | |
330ae7e9 MCC |
374 | So, 4.8-rc5 means that this is the fifth release candidate for the 4.8 |
375 | kernel and the patch should be applied on top of the 4.7 kernel source. | |
754c7976 JJ |
376 | |
377 | Here are 3 examples of how to apply these patches: | |
378 | ||
9299c3e9 MCC |
379 | :: |
380 | ||
330ae7e9 MCC |
381 | # first an example of moving from 4.7 to 4.8-rc3 |
382 | ||
383 | $ cd ~/linux-4.7 # change to the 4.7 source dir | |
384 | $ patch -p1 < ../patch-4.8-rc3 # apply the 4.8-rc3 patch | |
9299c3e9 | 385 | $ cd .. |
330ae7e9 | 386 | $ mv linux-4.7 linux-4.8-rc3 # rename the source dir |
754c7976 | 387 | |
330ae7e9 MCC |
388 | # now let's move from 4.8-rc3 to 4.8-rc5 |
389 | ||
390 | $ cd ~/linux-4.8-rc3 # change to the 4.8-rc3 dir | |
391 | $ patch -p1 -R < ../patch-4.8-rc3 # revert the 4.8-rc3 patch | |
392 | $ patch -p1 < ../patch-4.8-rc5 # apply the new 4.8-rc5 patch | |
9299c3e9 | 393 | $ cd .. |
330ae7e9 MCC |
394 | $ mv linux-4.8-rc3 linux-4.8-rc5 # rename the source dir |
395 | ||
396 | # finally let's try and move from 4.7.3 to 4.8-rc5 | |
754c7976 | 397 | |
330ae7e9 MCC |
398 | $ cd ~/linux-4.7.3 # change to the kernel source dir |
399 | $ patch -p1 -R < ../patch-4.7.3 # revert the 4.7.3 patch | |
400 | $ patch -p1 < ../patch-4.8-rc5 # apply new 4.8-rc5 patch | |
9299c3e9 | 401 | $ cd .. |
330ae7e9 | 402 | $ mv linux-4.7.3 linux-4.8-rc5 # rename the kernel source dir |
754c7976 JJ |
403 | |
404 | ||
405 | The -git kernels | |
9299c3e9 MCC |
406 | ================ |
407 | ||
408 | These are daily snapshots of Linus' kernel tree (managed in a git | |
754c7976 JJ |
409 | repository, hence the name). |
410 | ||
411 | These patches are usually released daily and represent the current state of | |
c594a50d | 412 | Linus's tree. They are more experimental than -rc kernels since they are |
754c7976 JJ |
413 | generated automatically without even a cursory glance to see if they are |
414 | sane. | |
415 | ||
330ae7e9 MCC |
416 | -git patches are not incremental and apply either to a base 4.x kernel or |
417 | a base 4.x-rc kernel -- you can see which from their name. | |
418 | A patch named 4.7-git1 applies to the 4.7 kernel source and a patch | |
419 | named 4.8-rc3-git2 applies to the source of the 4.8-rc3 kernel. | |
754c7976 JJ |
420 | |
421 | Here are some examples of how to apply these patches: | |
422 | ||
9299c3e9 | 423 | :: |
754c7976 | 424 | |
330ae7e9 | 425 | # moving from 4.7 to 4.7-git1 |
754c7976 | 426 | |
330ae7e9 MCC |
427 | $ cd ~/linux-4.7 # change to the kernel source dir |
428 | $ patch -p1 < ../patch-4.7-git1 # apply the 4.7-git1 patch | |
429 | $ cd .. | |
430 | $ mv linux-4.7 linux-4.7-git1 # rename the kernel source dir | |
754c7976 | 431 | |
330ae7e9 | 432 | # moving from 4.7-git1 to 4.8-rc2-git3 |
9299c3e9 | 433 | |
330ae7e9 MCC |
434 | $ cd ~/linux-4.7-git1 # change to the kernel source dir |
435 | $ patch -p1 -R < ../patch-4.7-git1 # revert the 4.7-git1 patch | |
436 | # we now have a 4.7 kernel | |
437 | $ patch -p1 < ../patch-4.8-rc2 # apply the 4.8-rc2 patch | |
438 | # the kernel is now 4.8-rc2 | |
439 | $ patch -p1 < ../patch-4.8-rc2-git3 # apply the 4.8-rc2-git3 patch | |
440 | # the kernel is now 4.8-rc2-git3 | |
441 | $ cd .. | |
442 | $ mv linux-4.7-git1 linux-4.8-rc2-git3 # rename source dir | |
754c7976 | 443 | |
9299c3e9 | 444 | |
330ae7e9 MCC |
445 | The -mm patches and the linux-next tree |
446 | ======================================= | |
754c7976 | 447 | |
330ae7e9 | 448 | The -mm patches are experimental patches released by Andrew Morton. |
9299c3e9 | 449 | |
330ae7e9 MCC |
450 | In the past, -mm tree were used to also test subsystem patches, but this |
451 | function is now done via the | |
452 | :ref:`linux-next <https://www.kernel.org/doc/man-pages/linux-next.html>` | |
453 | tree. The Subsystem maintainers push their patches first to linux-next, | |
454 | and, during the merge window, sends them directly to Linus. | |
754c7976 | 455 | |
330ae7e9 MCC |
456 | The -mm patches serve as a sort of proving ground for new features and other |
457 | experimental patches that aren't merged via a subsystem tree. | |
458 | Once such patches has proved its worth in -mm for a while Andrew pushes | |
459 | it on to Linus for inclusion in mainline. | |
754c7976 | 460 | |
330ae7e9 MCC |
461 | The linux-next tree is daily updated, and includes the -mm patches. |
462 | Both are in constant flux and contains many experimental features, a | |
c594a50d | 463 | lot of debugging patches not appropriate for mainline etc., and is the most |
754c7976 JJ |
464 | experimental of the branches described in this document. |
465 | ||
330ae7e9 | 466 | These patches are not appropriate for use on systems that are supposed to be |
754c7976 | 467 | stable and they are more risky to run than any of the other branches (make |
c594a50d | 468 | sure you have up-to-date backups -- that goes for any experimental kernel but |
330ae7e9 | 469 | even more so for -mm patches or using a Kernel from the linux-next tree). |
754c7976 | 470 | |
330ae7e9 MCC |
471 | Testing of -mm patches and linux-next is greatly appreciated since the whole |
472 | point of those are to weed out regressions, crashes, data corruption bugs, | |
473 | build breakage (and any other bug in general) before changes are merged into | |
474 | the more stable mainline Linus tree. | |
9299c3e9 | 475 | |
330ae7e9 MCC |
476 | But testers of -mm and linux-next should be aware that breakages are |
477 | more common than in any other tree. | |
754c7976 JJ |
478 | |
479 | ||
90f2447d JJ |
480 | This concludes this list of explanations of the various kernel trees. |
481 | I hope you are now clear on how to apply the various patches and help testing | |
482 | the kernel. | |
483 | ||
484 | Thank you's to Randy Dunlap, Rolf Eike Beer, Linus Torvalds, Bodo Eggert, | |
485 | Johannes Stezenbach, Grant Coady, Pavel Machek and others that I may have | |
486 | forgotten for their reviews and contributions to this document. | |
754c7976 | 487 |