1 .. _applying_patches: 1 .. _applying_patches:
2 2
3 Applying Patches To The Linux Kernel 3 Applying Patches To The Linux Kernel
4 ++++++++++++++++++++++++++++++++++++ 4 ++++++++++++++++++++++++++++++++++++
5 5
6 Original by: 6 Original by:
7 Jesper Juhl, August 2005 7 Jesper Juhl, August 2005
8 8
9 .. note:: 9 .. note::
10 10
11 This document is obsolete. In most cases, 11 This document is obsolete. In most cases, rather than using ``patch``
12 manually, you'll almost certainly want to l 12 manually, you'll almost certainly want to look at using Git instead.
13 13
14 A frequently asked question on the Linux Kerne 14 A frequently asked question on the Linux Kernel Mailing List is how to apply
15 a patch to the kernel or, more specifically, w 15 a patch to the kernel or, more specifically, what base kernel a patch for
16 one of the many trees/branches should be appli 16 one of the many trees/branches should be applied to. Hopefully this document
17 will explain this to you. 17 will explain this to you.
18 18
19 In addition to explaining how to apply and rev 19 In addition to explaining how to apply and revert patches, a brief
20 description of the different kernel trees (and 20 description of the different kernel trees (and examples of how to apply
21 their specific patches) is also provided. 21 their specific patches) is also provided.
22 22
23 23
24 What is a patch? 24 What is a patch?
25 ================ 25 ================
26 26
27 A patch is a small text document containing a 27 A patch is a small text document containing a delta of changes between two
28 different versions of a source tree. Patches a 28 different versions of a source tree. Patches are created with the ``diff``
29 program. 29 program.
30 30
31 To correctly apply a patch you need to know wh 31 To correctly apply a patch you need to know what base it was generated from
32 and what new version the patch will change the 32 and what new version the patch will change the source tree into. These
33 should both be present in the patch file metad 33 should both be present in the patch file metadata or be possible to deduce
34 from the filename. 34 from the filename.
35 35
36 36
37 How do I apply or revert a patch? 37 How do I apply or revert a patch?
38 ================================= 38 =================================
39 39
40 You apply a patch with the ``patch`` program. 40 You apply a patch with the ``patch`` program. The patch program reads a diff
41 (or patch) file and makes the changes to the s 41 (or patch) file and makes the changes to the source tree described in it.
42 42
43 Patches for the Linux kernel are generated rel 43 Patches for the Linux kernel are generated relative to the parent directory
44 holding the kernel source dir. 44 holding the kernel source dir.
45 45
46 This means that paths to files inside the patc 46 This means that paths to files inside the patch file contain the name of the
47 kernel source directories it was generated aga 47 kernel source directories it was generated against (or some other directory
48 names like "a/" and "b/"). 48 names like "a/" and "b/").
49 49
50 Since this is unlikely to match the name of th 50 Since this is unlikely to match the name of the kernel source dir on your
51 local machine (but is often useful info to see 51 local machine (but is often useful info to see what version an otherwise
52 unlabeled patch was generated against) you sho 52 unlabeled patch was generated against) you should change into your kernel
53 source directory and then strip the first elem 53 source directory and then strip the first element of the path from filenames
54 in the patch file when applying it (the ``-p1` 54 in the patch file when applying it (the ``-p1`` argument to ``patch`` does
55 this). 55 this).
56 56
57 To revert a previously applied patch, use the 57 To revert a previously applied patch, use the -R argument to patch.
58 So, if you applied a patch like this:: 58 So, if you applied a patch like this::
59 59
60 patch -p1 < ../patch-x.y.z 60 patch -p1 < ../patch-x.y.z
61 61
62 You can revert (undo) it like this:: 62 You can revert (undo) it like this::
63 63
64 patch -R -p1 < ../patch-x.y.z 64 patch -R -p1 < ../patch-x.y.z
65 65
66 66
67 How do I feed a patch/diff file to ``patch``? 67 How do I feed a patch/diff file to ``patch``?
68 ============================================= 68 =============================================
69 69
70 This (as usual with Linux and other UNIX like 70 This (as usual with Linux and other UNIX like operating systems) can be
71 done in several different ways. 71 done in several different ways.
72 72
73 In all the examples below I feed the file (in 73 In all the examples below I feed the file (in uncompressed form) to patch
74 via stdin using the following syntax:: 74 via stdin using the following syntax::
75 75
76 patch -p1 < path/to/patch-x.y.z 76 patch -p1 < path/to/patch-x.y.z
77 77
78 If you just want to be able to follow the exam 78 If you just want to be able to follow the examples below and don't want to
79 know of more than one way to use patch, then y 79 know of more than one way to use patch, then you can stop reading this
80 section here. 80 section here.
81 81
82 Patch can also get the name of the file to use 82 Patch can also get the name of the file to use via the -i argument, like
83 this:: 83 this::
84 84
85 patch -p1 -i path/to/patch-x.y.z 85 patch -p1 -i path/to/patch-x.y.z
86 86
87 If your patch file is compressed with gzip or 87 If your patch file is compressed with gzip or xz and you don't want to
88 uncompress it before applying it, then you can 88 uncompress it before applying it, then you can feed it to patch like this
89 instead:: 89 instead::
90 90
91 xzcat path/to/patch-x.y.z.xz | patch - 91 xzcat path/to/patch-x.y.z.xz | patch -p1
92 bzcat path/to/patch-x.y.z.gz | patch - 92 bzcat path/to/patch-x.y.z.gz | patch -p1
93 93
94 If you wish to uncompress the patch file by ha 94 If you wish to uncompress the patch file by hand first before applying it
95 (what I assume you've done in the examples bel 95 (what I assume you've done in the examples below), then you simply run
96 gunzip or xz on the file -- like this:: 96 gunzip or xz on the file -- like this::
97 97
98 gunzip patch-x.y.z.gz 98 gunzip patch-x.y.z.gz
99 xz -d patch-x.y.z.xz 99 xz -d patch-x.y.z.xz
100 100
101 Which will leave you with a plain text patch-x 101 Which will leave you with a plain text patch-x.y.z file that you can feed to
102 patch via stdin or the ``-i`` argument, as you 102 patch via stdin or the ``-i`` argument, as you prefer.
103 103
104 A few other nice arguments for patch are ``-s` 104 A few other nice arguments for patch are ``-s`` which causes patch to be silent
105 except for errors which is nice to prevent err 105 except for errors which is nice to prevent errors from scrolling out of the
106 screen too fast, and ``--dry-run`` which cause 106 screen too fast, and ``--dry-run`` which causes patch to just print a listing of
107 what would happen, but doesn't actually make a 107 what would happen, but doesn't actually make any changes. Finally ``--verbose``
108 tells patch to print more information about th 108 tells patch to print more information about the work being done.
109 109
110 110
111 Common errors when patching 111 Common errors when patching
112 =========================== 112 ===========================
113 113
114 When patch applies a patch file it attempts to 114 When patch applies a patch file it attempts to verify the sanity of the
115 file in different ways. 115 file in different ways.
116 116
117 Checking that the file looks like a valid patc 117 Checking that the file looks like a valid patch file and checking the code
118 around the bits being modified matches the con 118 around the bits being modified matches the context provided in the patch are
119 just two of the basic sanity checks patch does 119 just two of the basic sanity checks patch does.
120 120
121 If patch encounters something that doesn't loo 121 If patch encounters something that doesn't look quite right it has two
122 options. It can either refuse to apply the cha 122 options. It can either refuse to apply the changes and abort or it can try
123 to find a way to make the patch apply with a f 123 to find a way to make the patch apply with a few minor changes.
124 124
125 One example of something that's not 'quite rig 125 One example of something that's not 'quite right' that patch will attempt to
126 fix up is if all the context matches, the line 126 fix up is if all the context matches, the lines being changed match, but the
127 line numbers are different. This can happen, f 127 line numbers are different. This can happen, for example, if the patch makes
128 a change in the middle of the file but for som 128 a change in the middle of the file but for some reasons a few lines have
129 been added or removed near the beginning of th 129 been added or removed near the beginning of the file. In that case
130 everything looks good it has just moved up or 130 everything looks good it has just moved up or down a bit, and patch will
131 usually adjust the line numbers and apply the 131 usually adjust the line numbers and apply the patch.
132 132
133 Whenever patch applies a patch that it had to 133 Whenever patch applies a patch that it had to modify a bit to make it fit
134 it'll tell you about it by saying the patch ap 134 it'll tell you about it by saying the patch applied with **fuzz**.
135 You should be wary of such changes since even 135 You should be wary of such changes since even though patch probably got it
136 right it doesn't /always/ get it right, and th 136 right it doesn't /always/ get it right, and the result will sometimes be
137 wrong. 137 wrong.
138 138
139 When patch encounters a change that it can't f 139 When patch encounters a change that it can't fix up with fuzz it rejects it
140 outright and leaves a file with a ``.rej`` ext 140 outright and leaves a file with a ``.rej`` extension (a reject file). You can
141 read this file to see exactly what change coul 141 read this file to see exactly what change couldn't be applied, so you can
142 go fix it up by hand if you wish. 142 go fix it up by hand if you wish.
143 143
144 If you don't have any third-party patches appl 144 If you don't have any third-party patches applied to your kernel source, but
145 only patches from kernel.org and you apply the 145 only patches from kernel.org and you apply the patches in the correct order,
146 and have made no modifications yourself to the 146 and have made no modifications yourself to the source files, then you should
147 never see a fuzz or reject message from patch. 147 never see a fuzz or reject message from patch. If you do see such messages
148 anyway, then there's a high risk that either y 148 anyway, then there's a high risk that either your local source tree or the
149 patch file is corrupted in some way. In that c 149 patch file is corrupted in some way. In that case you should probably try
150 re-downloading the patch and if things are sti 150 re-downloading the patch and if things are still not OK then you'd be advised
151 to start with a fresh tree downloaded in full 151 to start with a fresh tree downloaded in full from kernel.org.
152 152
153 Let's look a bit more at some of the messages 153 Let's look a bit more at some of the messages patch can produce.
154 154
155 If patch stops and presents a ``File to patch: 155 If patch stops and presents a ``File to patch:`` prompt, then patch could not
156 find a file to be patched. Most likely you for 156 find a file to be patched. Most likely you forgot to specify -p1 or you are
157 in the wrong directory. Less often, you'll fin 157 in the wrong directory. Less often, you'll find patches that need to be
158 applied with ``-p0`` instead of ``-p1`` (readi 158 applied with ``-p0`` instead of ``-p1`` (reading the patch file should reveal if
159 this is the case -- if so, then this is an err 159 this is the case -- if so, then this is an error by the person who created
160 the patch but is not fatal). 160 the patch but is not fatal).
161 161
162 If you get ``Hunk #2 succeeded at 1887 with fu 162 If you get ``Hunk #2 succeeded at 1887 with fuzz 2 (offset 7 lines).`` or a
163 message similar to that, then it means that pa 163 message similar to that, then it means that patch had to adjust the location
164 of the change (in this example it needed to mo 164 of the change (in this example it needed to move 7 lines from where it
165 expected to make the change to make it fit). 165 expected to make the change to make it fit).
166 166
167 The resulting file may or may not be OK, depen 167 The resulting file may or may not be OK, depending on the reason the file
168 was different than expected. 168 was different than expected.
169 169
170 This often happens if you try to apply a patch 170 This often happens if you try to apply a patch that was generated against a
171 different kernel version than the one you are 171 different kernel version than the one you are trying to patch.
172 172
173 If you get a message like ``Hunk #3 FAILED at 173 If you get a message like ``Hunk #3 FAILED at 2387.``, then it means that the
174 patch could not be applied correctly and the p 174 patch could not be applied correctly and the patch program was unable to
175 fuzz its way through. This will generate a ``. 175 fuzz its way through. This will generate a ``.rej`` file with the change that
176 caused the patch to fail and also a ``.orig`` 176 caused the patch to fail and also a ``.orig`` file showing you the original
177 content that couldn't be changed. 177 content that couldn't be changed.
178 178
179 If you get ``Reversed (or previously applied) 179 If you get ``Reversed (or previously applied) patch detected! Assume -R? [n]``
180 then patch detected that the change contained 180 then patch detected that the change contained in the patch seems to have
181 already been made. 181 already been made.
182 182
183 If you actually did apply this patch previousl 183 If you actually did apply this patch previously and you just re-applied it
184 in error, then just say [n]o and abort this pa 184 in error, then just say [n]o and abort this patch. If you applied this patch
185 previously and actually intended to revert it, 185 previously and actually intended to revert it, but forgot to specify -R,
186 then you can say [**y**]es here to make patch 186 then you can say [**y**]es here to make patch revert it for you.
187 187
188 This can also happen if the creator of the pat 188 This can also happen if the creator of the patch reversed the source and
189 destination directories when creating the patc 189 destination directories when creating the patch, and in that case reverting
190 the patch will in fact apply it. 190 the patch will in fact apply it.
191 191
192 A message similar to ``patch: **** unexpected 192 A message similar to ``patch: **** unexpected end of file in patch`` or
193 ``patch unexpectedly ends in middle of line`` 193 ``patch unexpectedly ends in middle of line`` means that patch could make no
194 sense of the file you fed to it. Either your d 194 sense of the file you fed to it. Either your download is broken, you tried to
195 feed patch a compressed patch file without unc 195 feed patch a compressed patch file without uncompressing it first, or the patch
196 file that you are using has been mangled by a 196 file that you are using has been mangled by a mail client or mail transfer
197 agent along the way somewhere, e.g., by splitt 197 agent along the way somewhere, e.g., by splitting a long line into two lines.
198 Often these warnings can easily be fixed by jo 198 Often these warnings can easily be fixed by joining (concatenating) the
199 two lines that had been split. 199 two lines that had been split.
200 200
201 As I already mentioned above, these errors sho 201 As I already mentioned above, these errors should never happen if you apply
202 a patch from kernel.org to the correct version 202 a patch from kernel.org to the correct version of an unmodified source tree.
203 So if you get these errors with kernel.org pat 203 So if you get these errors with kernel.org patches then you should probably
204 assume that either your patch file or your tre 204 assume that either your patch file or your tree is broken and I'd advise you
205 to start over with a fresh download of a full 205 to start over with a fresh download of a full kernel tree and the patch you
206 wish to apply. 206 wish to apply.
207 207
208 208
209 Are there any alternatives to ``patch``? 209 Are there any alternatives to ``patch``?
210 ======================================== 210 ========================================
211 211
212 212
213 Yes there are alternatives. 213 Yes there are alternatives.
214 214
215 You can use the ``interdiff`` program (http:// 215 You can use the ``interdiff`` program (http://cyberelk.net/tim/patchutils/) to
216 generate a patch representing the differences 216 generate a patch representing the differences between two patches and then
217 apply the result. 217 apply the result.
218 218
219 This will let you move from something like 5.7 219 This will let you move from something like 5.7.2 to 5.7.3 in a single
220 step. The -z flag to interdiff will even let y 220 step. The -z flag to interdiff will even let you feed it patches in gzip or
221 bzip2 compressed form directly without the use 221 bzip2 compressed form directly without the use of zcat or bzcat or manual
222 decompression. 222 decompression.
223 223
224 Here's how you'd go from 5.7.2 to 5.7.3 in a s 224 Here's how you'd go from 5.7.2 to 5.7.3 in a single step::
225 225
226 interdiff -z ../patch-5.7.2.gz ../patc 226 interdiff -z ../patch-5.7.2.gz ../patch-5.7.3.gz | patch -p1
227 227
228 Although interdiff may save you a step or two 228 Although interdiff may save you a step or two you are generally advised to
229 do the additional steps since interdiff can ge 229 do the additional steps since interdiff can get things wrong in some cases.
230 230
231 Another alternative is ``ketchup``, which is a 231 Another alternative is ``ketchup``, which is a python script for automatic
232 downloading and applying of patches (https://w 232 downloading and applying of patches (https://www.selenic.com/ketchup/).
233 233
234 Other nice tools are diffstat, which shows a s 234 Other nice tools are diffstat, which shows a summary of changes made by a
235 patch; lsdiff, which displays a short listing 235 patch; lsdiff, which displays a short listing of affected files in a patch
236 file, along with (optionally) the line numbers 236 file, along with (optionally) the line numbers of the start of each patch;
237 and grepdiff, which displays a list of the fil 237 and grepdiff, which displays a list of the files modified by a patch where
238 the patch contains a given regular expression. 238 the patch contains a given regular expression.
239 239
240 240
241 Where can I download the patches? 241 Where can I download the patches?
242 ================================= 242 =================================
243 243
244 The patches are available at https://kernel.or 244 The patches are available at https://kernel.org/
245 Most recent patches are linked from the front 245 Most recent patches are linked from the front page, but they also have
246 specific homes. 246 specific homes.
247 247
248 The 5.x.y (-stable) and 5.x patches live at 248 The 5.x.y (-stable) and 5.x patches live at
249 249
250 https://www.kernel.org/pub/linux/kerne 250 https://www.kernel.org/pub/linux/kernel/v5.x/
251 251
252 The 5.x.y incremental patches live at 252 The 5.x.y incremental patches live at
253 253
254 https://www.kernel.org/pub/linux/kerne 254 https://www.kernel.org/pub/linux/kernel/v5.x/incr/
255 255
256 The -rc patches are not stored on the webserve 256 The -rc patches are not stored on the webserver but are generated on
257 demand from git tags such as 257 demand from git tags such as
258 258
259 https://git.kernel.org/torvalds/p/v5.1 259 https://git.kernel.org/torvalds/p/v5.1-rc1/v5.0
260 260
261 The stable -rc patches live at 261 The stable -rc patches live at
262 262
263 https://www.kernel.org/pub/linux/kerne 263 https://www.kernel.org/pub/linux/kernel/v5.x/stable-review/
264 264
265 265
266 The 5.x kernels 266 The 5.x kernels
267 =============== 267 ===============
268 268
269 These are the base stable releases released by 269 These are the base stable releases released by Linus. The highest numbered
270 release is the most recent. 270 release is the most recent.
271 271
272 If regressions or other serious flaws are foun 272 If regressions or other serious flaws are found, then a -stable fix patch
273 will be released (see below) on top of this ba 273 will be released (see below) on top of this base. Once a new 5.x base
274 kernel is released, a patch is made available 274 kernel is released, a patch is made available that is a delta between the
275 previous 5.x kernel and the new one. 275 previous 5.x kernel and the new one.
276 276
277 To apply a patch moving from 5.6 to 5.7, you'd 277 To apply a patch moving from 5.6 to 5.7, you'd do the following (note
278 that such patches do **NOT** apply on top of 5 278 that such patches do **NOT** apply on top of 5.x.y kernels but on top of the
279 base 5.x kernel -- if you need to move from 5. 279 base 5.x kernel -- if you need to move from 5.x.y to 5.x+1 you need to
280 first revert the 5.x.y patch). 280 first revert the 5.x.y patch).
281 281
282 Here are some examples:: 282 Here are some examples::
283 283
284 # moving from 5.6 to 5.7 284 # moving from 5.6 to 5.7
285 285
286 $ cd ~/linux-5.6 # chan 286 $ cd ~/linux-5.6 # change to kernel source dir
287 $ patch -p1 < ../patch-5.7 # appl 287 $ patch -p1 < ../patch-5.7 # apply the 5.7 patch
288 $ cd .. 288 $ cd ..
289 $ mv linux-5.6 linux-5.7 # rena 289 $ mv linux-5.6 linux-5.7 # rename source dir
290 290
291 # moving from 5.6.1 to 5.7 291 # moving from 5.6.1 to 5.7
292 292
293 $ cd ~/linux-5.6.1 # chan 293 $ cd ~/linux-5.6.1 # change to kernel source dir
294 $ patch -p1 -R < ../patch-5.6.1 # reve 294 $ patch -p1 -R < ../patch-5.6.1 # revert the 5.6.1 patch
295 # sour 295 # source dir is now 5.6
296 $ patch -p1 < ../patch-5.7 # appl 296 $ patch -p1 < ../patch-5.7 # apply new 5.7 patch
297 $ cd .. 297 $ cd ..
298 $ mv linux-5.6.1 linux-5.7 # rena 298 $ mv linux-5.6.1 linux-5.7 # rename source dir
299 299
300 300
301 The 5.x.y kernels 301 The 5.x.y kernels
302 ================= 302 =================
303 303
304 Kernels with 3-digit versions are -stable kern 304 Kernels with 3-digit versions are -stable kernels. They contain small(ish)
305 critical fixes for security problems or signif 305 critical fixes for security problems or significant regressions discovered
306 in a given 5.x kernel. 306 in a given 5.x kernel.
307 307
308 This is the recommended branch for users who w 308 This is the recommended branch for users who want the most recent stable
309 kernel and are not interested in helping test 309 kernel and are not interested in helping test development/experimental
310 versions. 310 versions.
311 311
312 If no 5.x.y kernel is available, then the high 312 If no 5.x.y kernel is available, then the highest numbered 5.x kernel is
313 the current stable kernel. 313 the current stable kernel.
314 314
315 The -stable team provides normal as well as in 315 The -stable team provides normal as well as incremental patches. Below is
316 how to apply these patches. 316 how to apply these patches.
317 317
318 Normal patches 318 Normal patches
319 ~~~~~~~~~~~~~~ 319 ~~~~~~~~~~~~~~
320 320
321 These patches are not incremental, meaning tha 321 These patches are not incremental, meaning that for example the 5.7.3
322 patch does not apply on top of the 5.7.2 kerne 322 patch does not apply on top of the 5.7.2 kernel source, but rather on top
323 of the base 5.7 kernel source. 323 of the base 5.7 kernel source.
324 324
325 So, in order to apply the 5.7.3 patch to your 325 So, in order to apply the 5.7.3 patch to your existing 5.7.2 kernel
326 source you have to first back out the 5.7.2 pa 326 source you have to first back out the 5.7.2 patch (so you are left with a
327 base 5.7 kernel source) and then apply the new 327 base 5.7 kernel source) and then apply the new 5.7.3 patch.
328 328
329 Here's a small example:: 329 Here's a small example::
330 330
331 $ cd ~/linux-5.7.2 # chan 331 $ cd ~/linux-5.7.2 # change to the kernel source dir
332 $ patch -p1 -R < ../patch-5.7.2 # reve 332 $ patch -p1 -R < ../patch-5.7.2 # revert the 5.7.2 patch
333 $ patch -p1 < ../patch-5.7.3 # appl 333 $ patch -p1 < ../patch-5.7.3 # apply the new 5.7.3 patch
334 $ cd .. 334 $ cd ..
335 $ mv linux-5.7.2 linux-5.7.3 # rena 335 $ mv linux-5.7.2 linux-5.7.3 # rename the kernel source dir
336 336
337 Incremental patches 337 Incremental patches
338 ~~~~~~~~~~~~~~~~~~~ 338 ~~~~~~~~~~~~~~~~~~~
339 339
340 Incremental patches are different: instead of 340 Incremental patches are different: instead of being applied on top
341 of base 5.x kernel, they are applied on top of 341 of base 5.x kernel, they are applied on top of previous stable kernel
342 (5.x.y-1). 342 (5.x.y-1).
343 343
344 Here's the example to apply these:: 344 Here's the example to apply these::
345 345
346 $ cd ~/linux-5.7.2 # chan 346 $ cd ~/linux-5.7.2 # change to the kernel source dir
347 $ patch -p1 < ../patch-5.7.2-3 # appl 347 $ patch -p1 < ../patch-5.7.2-3 # apply the new 5.7.3 patch
348 $ cd .. 348 $ cd ..
349 $ mv linux-5.7.2 linux-5.7.3 # rena 349 $ mv linux-5.7.2 linux-5.7.3 # rename the kernel source dir
350 350
351 351
352 The -rc kernels 352 The -rc kernels
353 =============== 353 ===============
354 354
355 These are release-candidate kernels. These are 355 These are release-candidate kernels. These are development kernels released
356 by Linus whenever he deems the current git (th 356 by Linus whenever he deems the current git (the kernel's source management
357 tool) tree to be in a reasonably sane state ad 357 tool) tree to be in a reasonably sane state adequate for testing.
358 358
359 These kernels are not stable and you should ex 359 These kernels are not stable and you should expect occasional breakage if
360 you intend to run them. This is however the mo 360 you intend to run them. This is however the most stable of the main
361 development branches and is also what will eve 361 development branches and is also what will eventually turn into the next
362 stable kernel, so it is important that it be t 362 stable kernel, so it is important that it be tested by as many people as
363 possible. 363 possible.
364 364
365 This is a good branch to run for people who wa 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 som 366 development kernels but do not want to run some of the really experimental
367 stuff (such people should see the sections abo 367 stuff (such people should see the sections about -next and -mm kernels below).
368 368
369 The -rc patches are not incremental, they appl 369 The -rc patches are not incremental, they apply to a base 5.x kernel, just
370 like the 5.x.y patches described above. The ke 370 like the 5.x.y patches described above. The kernel version before the -rcN
371 suffix denotes the version of the kernel that 371 suffix denotes the version of the kernel that this -rc kernel will eventually
372 turn into. 372 turn into.
373 373
374 So, 5.8-rc5 means that this is the fifth relea 374 So, 5.8-rc5 means that this is the fifth release candidate for the 5.8
375 kernel and the patch should be applied on top 375 kernel and the patch should be applied on top of the 5.7 kernel source.
376 376
377 Here are 3 examples of how to apply these patc 377 Here are 3 examples of how to apply these patches::
378 378
379 # first an example of moving from 5.7 379 # first an example of moving from 5.7 to 5.8-rc3
380 380
381 $ cd ~/linux-5.7 381 $ cd ~/linux-5.7 # change to the 5.7 source dir
382 $ patch -p1 < ../patch-5.8-rc3 382 $ patch -p1 < ../patch-5.8-rc3 # apply the 5.8-rc3 patch
383 $ cd .. 383 $ cd ..
384 $ mv linux-5.7 linux-5.8-rc3 384 $ mv linux-5.7 linux-5.8-rc3 # rename the source dir
385 385
386 # now let's move from 5.8-rc3 to 5.8-r 386 # now let's move from 5.8-rc3 to 5.8-rc5
387 387
388 $ cd ~/linux-5.8-rc3 388 $ cd ~/linux-5.8-rc3 # change to the 5.8-rc3 dir
389 $ patch -p1 -R < ../patch-5.8-rc3 389 $ patch -p1 -R < ../patch-5.8-rc3 # revert the 5.8-rc3 patch
390 $ patch -p1 < ../patch-5.8-rc5 390 $ patch -p1 < ../patch-5.8-rc5 # apply the new 5.8-rc5 patch
391 $ cd .. 391 $ cd ..
392 $ mv linux-5.8-rc3 linux-5.8-rc5 392 $ mv linux-5.8-rc3 linux-5.8-rc5 # rename the source dir
393 393
394 # finally let's try and move from 5.7. 394 # finally let's try and move from 5.7.3 to 5.8-rc5
395 395
396 $ cd ~/linux-5.7.3 396 $ cd ~/linux-5.7.3 # change to the kernel source dir
397 $ patch -p1 -R < ../patch-5.7.3 397 $ patch -p1 -R < ../patch-5.7.3 # revert the 5.7.3 patch
398 $ patch -p1 < ../patch-5.8-rc5 398 $ patch -p1 < ../patch-5.8-rc5 # apply new 5.8-rc5 patch
399 $ cd .. 399 $ cd ..
400 $ mv linux-5.7.3 linux-5.8-rc5 400 $ mv linux-5.7.3 linux-5.8-rc5 # rename the kernel source dir
401 401
402 402
403 The -mm patches and the linux-next tree 403 The -mm patches and the linux-next tree
404 ======================================= 404 =======================================
405 405
406 The -mm patches are experimental patches relea 406 The -mm patches are experimental patches released by Andrew Morton.
407 407
408 In the past, -mm tree were used to also test s 408 In the past, -mm tree were used to also test subsystem patches, but this
409 function is now done via the 409 function is now done via the
410 `linux-next` (https://www.kernel.org/doc/man-p 410 `linux-next` (https://www.kernel.org/doc/man-pages/linux-next.html)
411 tree. The Subsystem maintainers push their pat 411 tree. The Subsystem maintainers push their patches first to linux-next,
412 and, during the merge window, sends them direc 412 and, during the merge window, sends them directly to Linus.
413 413
414 The -mm patches serve as a sort of proving gro 414 The -mm patches serve as a sort of proving ground for new features and other
415 experimental patches that aren't merged via a 415 experimental patches that aren't merged via a subsystem tree.
416 Once such patches has proved its worth in -mm 416 Once such patches has proved its worth in -mm for a while Andrew pushes
417 it on to Linus for inclusion in mainline. 417 it on to Linus for inclusion in mainline.
418 418
419 The linux-next tree is daily updated, and incl 419 The linux-next tree is daily updated, and includes the -mm patches.
420 Both are in constant flux and contains many ex 420 Both are in constant flux and contains many experimental features, a
421 lot of debugging patches not appropriate for m 421 lot of debugging patches not appropriate for mainline etc., and is the most
422 experimental of the branches described in this 422 experimental of the branches described in this document.
423 423
424 These patches are not appropriate for use on s 424 These patches are not appropriate for use on systems that are supposed to be
425 stable and they are more risky to run than any 425 stable and they are more risky to run than any of the other branches (make
426 sure you have up-to-date backups -- that goes 426 sure you have up-to-date backups -- that goes for any experimental kernel but
427 even more so for -mm patches or using a Kernel 427 even more so for -mm patches or using a Kernel from the linux-next tree).
428 428
429 Testing of -mm patches and linux-next is great 429 Testing of -mm patches and linux-next is greatly appreciated since the whole
430 point of those are to weed out regressions, cr 430 point of those are to weed out regressions, crashes, data corruption bugs,
431 build breakage (and any other bug in general) 431 build breakage (and any other bug in general) before changes are merged into
432 the more stable mainline Linus tree. 432 the more stable mainline Linus tree.
433 433
434 But testers of -mm and linux-next should be aw 434 But testers of -mm and linux-next should be aware that breakages are
435 more common than in any other tree. 435 more common than in any other tree.
436 436
437 437
438 This concludes this list of explanations of th 438 This concludes this list of explanations of the various kernel trees.
439 I hope you are now clear on how to apply the v 439 I hope you are now clear on how to apply the various patches and help testing
440 the kernel. 440 the kernel.
441 441
442 Thank you's to Randy Dunlap, Rolf Eike Beer, L 442 Thank you's to Randy Dunlap, Rolf Eike Beer, Linus Torvalds, Bodo Eggert,
443 Johannes Stezenbach, Grant Coady, Pavel Machek 443 Johannes Stezenbach, Grant Coady, Pavel Machek and others that I may have
444 forgotten for their reviews and contributions 444 forgotten for their reviews and contributions to this document.
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