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 Last update:
>> 10 2016-09-14
>> 11
9 .. note:: 12 .. note::
10 13
11 This document is obsolete. In most cases, 14 This document is obsolete. In most cases, rather than using ``patch``
12 manually, you'll almost certainly want to l 15 manually, you'll almost certainly want to look at using Git instead.
13 16
14 A frequently asked question on the Linux Kerne 17 A frequently asked question on the Linux Kernel Mailing List is how to apply
15 a patch to the kernel or, more specifically, w 18 a patch to the kernel or, more specifically, what base kernel a patch for
16 one of the many trees/branches should be appli 19 one of the many trees/branches should be applied to. Hopefully this document
17 will explain this to you. 20 will explain this to you.
18 21
19 In addition to explaining how to apply and rev 22 In addition to explaining how to apply and revert patches, a brief
20 description of the different kernel trees (and 23 description of the different kernel trees (and examples of how to apply
21 their specific patches) is also provided. 24 their specific patches) is also provided.
22 25
23 26
24 What is a patch? 27 What is a patch?
25 ================ 28 ================
26 29
27 A patch is a small text document containing a 30 A patch is a small text document containing a delta of changes between two
28 different versions of a source tree. Patches a 31 different versions of a source tree. Patches are created with the ``diff``
29 program. 32 program.
30 33
31 To correctly apply a patch you need to know wh 34 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 35 and what new version the patch will change the source tree into. These
33 should both be present in the patch file metad 36 should both be present in the patch file metadata or be possible to deduce
34 from the filename. 37 from the filename.
35 38
36 39
37 How do I apply or revert a patch? 40 How do I apply or revert a patch?
38 ================================= 41 =================================
39 42
40 You apply a patch with the ``patch`` program. 43 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 44 (or patch) file and makes the changes to the source tree described in it.
42 45
43 Patches for the Linux kernel are generated rel 46 Patches for the Linux kernel are generated relative to the parent directory
44 holding the kernel source dir. 47 holding the kernel source dir.
45 48
46 This means that paths to files inside the patc 49 This means that paths to files inside the patch file contain the name of the
47 kernel source directories it was generated aga 50 kernel source directories it was generated against (or some other directory
48 names like "a/" and "b/"). 51 names like "a/" and "b/").
49 52
50 Since this is unlikely to match the name of th 53 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 54 local machine (but is often useful info to see what version an otherwise
52 unlabeled patch was generated against) you sho 55 unlabeled patch was generated against) you should change into your kernel
53 source directory and then strip the first elem 56 source directory and then strip the first element of the path from filenames
54 in the patch file when applying it (the ``-p1` 57 in the patch file when applying it (the ``-p1`` argument to ``patch`` does
55 this). 58 this).
56 59
57 To revert a previously applied patch, use the 60 To revert a previously applied patch, use the -R argument to patch.
58 So, if you applied a patch like this:: 61 So, if you applied a patch like this::
59 62
60 patch -p1 < ../patch-x.y.z 63 patch -p1 < ../patch-x.y.z
61 64
62 You can revert (undo) it like this:: 65 You can revert (undo) it like this::
63 66
64 patch -R -p1 < ../patch-x.y.z 67 patch -R -p1 < ../patch-x.y.z
65 68
66 69
67 How do I feed a patch/diff file to ``patch``? 70 How do I feed a patch/diff file to ``patch``?
68 ============================================= 71 =============================================
69 72
70 This (as usual with Linux and other UNIX like 73 This (as usual with Linux and other UNIX like operating systems) can be
71 done in several different ways. 74 done in several different ways.
72 75
73 In all the examples below I feed the file (in 76 In all the examples below I feed the file (in uncompressed form) to patch
74 via stdin using the following syntax:: 77 via stdin using the following syntax::
75 78
76 patch -p1 < path/to/patch-x.y.z 79 patch -p1 < path/to/patch-x.y.z
77 80
78 If you just want to be able to follow the exam 81 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 82 know of more than one way to use patch, then you can stop reading this
80 section here. 83 section here.
81 84
82 Patch can also get the name of the file to use 85 Patch can also get the name of the file to use via the -i argument, like
83 this:: 86 this::
84 87
85 patch -p1 -i path/to/patch-x.y.z 88 patch -p1 -i path/to/patch-x.y.z
86 89
87 If your patch file is compressed with gzip or 90 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 91 uncompress it before applying it, then you can feed it to patch like this
89 instead:: 92 instead::
90 93
91 xzcat path/to/patch-x.y.z.xz | patch - 94 xzcat path/to/patch-x.y.z.xz | patch -p1
92 bzcat path/to/patch-x.y.z.gz | patch - 95 bzcat path/to/patch-x.y.z.gz | patch -p1
93 96
94 If you wish to uncompress the patch file by ha 97 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 98 (what I assume you've done in the examples below), then you simply run
96 gunzip or xz on the file -- like this:: 99 gunzip or xz on the file -- like this::
97 100
98 gunzip patch-x.y.z.gz 101 gunzip patch-x.y.z.gz
99 xz -d patch-x.y.z.xz 102 xz -d patch-x.y.z.xz
100 103
101 Which will leave you with a plain text patch-x 104 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 105 patch via stdin or the ``-i`` argument, as you prefer.
103 106
104 A few other nice arguments for patch are ``-s` 107 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 108 except for errors which is nice to prevent errors from scrolling out of the
106 screen too fast, and ``--dry-run`` which cause 109 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 110 what would happen, but doesn't actually make any changes. Finally ``--verbose``
108 tells patch to print more information about th 111 tells patch to print more information about the work being done.
109 112
110 113
111 Common errors when patching 114 Common errors when patching
112 =========================== 115 ===========================
113 116
114 When patch applies a patch file it attempts to 117 When patch applies a patch file it attempts to verify the sanity of the
115 file in different ways. 118 file in different ways.
116 119
117 Checking that the file looks like a valid patc 120 Checking that the file looks like a valid patch file and checking the code
118 around the bits being modified matches the con 121 around the bits being modified matches the context provided in the patch are
119 just two of the basic sanity checks patch does 122 just two of the basic sanity checks patch does.
120 123
121 If patch encounters something that doesn't loo 124 If patch encounters something that doesn't look quite right it has two
122 options. It can either refuse to apply the cha 125 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 126 to find a way to make the patch apply with a few minor changes.
124 127
125 One example of something that's not 'quite rig 128 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 129 fix up is if all the context matches, the lines being changed match, but the
127 line numbers are different. This can happen, f 130 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 131 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 132 been added or removed near the beginning of the file. In that case
130 everything looks good it has just moved up or 133 everything looks good it has just moved up or down a bit, and patch will
131 usually adjust the line numbers and apply the 134 usually adjust the line numbers and apply the patch.
132 135
133 Whenever patch applies a patch that it had to 136 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 137 it'll tell you about it by saying the patch applied with **fuzz**.
135 You should be wary of such changes since even 138 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 139 right it doesn't /always/ get it right, and the result will sometimes be
137 wrong. 140 wrong.
138 141
139 When patch encounters a change that it can't f 142 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 143 outright and leaves a file with a ``.rej`` extension (a reject file). You can
141 read this file to see exactly what change coul 144 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. 145 go fix it up by hand if you wish.
143 146
144 If you don't have any third-party patches appl 147 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 148 only patches from kernel.org and you apply the patches in the correct order,
146 and have made no modifications yourself to the 149 and have made no modifications yourself to the source files, then you should
147 never see a fuzz or reject message from patch. 150 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 151 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 152 patch file is corrupted in some way. In that case you should probably try
150 re-downloading the patch and if things are sti 153 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 154 to start with a fresh tree downloaded in full from kernel.org.
152 155
153 Let's look a bit more at some of the messages 156 Let's look a bit more at some of the messages patch can produce.
154 157
155 If patch stops and presents a ``File to patch: 158 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 159 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 160 in the wrong directory. Less often, you'll find patches that need to be
158 applied with ``-p0`` instead of ``-p1`` (readi 161 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 162 this is the case -- if so, then this is an error by the person who created
160 the patch but is not fatal). 163 the patch but is not fatal).
161 164
162 If you get ``Hunk #2 succeeded at 1887 with fu 165 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 166 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 167 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). 168 expected to make the change to make it fit).
166 169
167 The resulting file may or may not be OK, depen 170 The resulting file may or may not be OK, depending on the reason the file
168 was different than expected. 171 was different than expected.
169 172
170 This often happens if you try to apply a patch 173 This often happens if you try to apply a patch that was generated against a
171 different kernel version than the one you are 174 different kernel version than the one you are trying to patch.
172 175
173 If you get a message like ``Hunk #3 FAILED at 176 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 177 patch could not be applied correctly and the patch program was unable to
175 fuzz its way through. This will generate a ``. 178 fuzz its way through. This will generate a ``.rej`` file with the change that
176 caused the patch to fail and also a ``.orig`` 179 caused the patch to fail and also a ``.orig`` file showing you the original
177 content that couldn't be changed. 180 content that couldn't be changed.
178 181
179 If you get ``Reversed (or previously applied) 182 If you get ``Reversed (or previously applied) patch detected! Assume -R? [n]``
180 then patch detected that the change contained 183 then patch detected that the change contained in the patch seems to have
181 already been made. 184 already been made.
182 185
183 If you actually did apply this patch previousl 186 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 187 in error, then just say [n]o and abort this patch. If you applied this patch
185 previously and actually intended to revert it, 188 previously and actually intended to revert it, but forgot to specify -R,
186 then you can say [**y**]es here to make patch 189 then you can say [**y**]es here to make patch revert it for you.
187 190
188 This can also happen if the creator of the pat 191 This can also happen if the creator of the patch reversed the source and
189 destination directories when creating the patc 192 destination directories when creating the patch, and in that case reverting
190 the patch will in fact apply it. 193 the patch will in fact apply it.
191 194
192 A message similar to ``patch: **** unexpected 195 A message similar to ``patch: **** unexpected end of file in patch`` or
193 ``patch unexpectedly ends in middle of line`` 196 ``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 197 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 198 feed patch a compressed patch file without uncompressing it first, or the patch
196 file that you are using has been mangled by a 199 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 200 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 201 Often these warnings can easily be fixed by joining (concatenating) the
199 two lines that had been split. 202 two lines that had been split.
200 203
201 As I already mentioned above, these errors sho 204 As I already mentioned above, these errors should never happen if you apply
202 a patch from kernel.org to the correct version 205 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 206 So if you get these errors with kernel.org patches then you should probably
204 assume that either your patch file or your tre 207 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 208 to start over with a fresh download of a full kernel tree and the patch you
206 wish to apply. 209 wish to apply.
207 210
208 211
209 Are there any alternatives to ``patch``? 212 Are there any alternatives to ``patch``?
210 ======================================== 213 ========================================
211 214
212 215
213 Yes there are alternatives. 216 Yes there are alternatives.
214 217
215 You can use the ``interdiff`` program (http:// 218 You can use the ``interdiff`` program (http://cyberelk.net/tim/patchutils/) to
216 generate a patch representing the differences 219 generate a patch representing the differences between two patches and then
217 apply the result. 220 apply the result.
218 221
219 This will let you move from something like 5.7 !! 222 This will let you move from something like 4.7.2 to 4.7.3 in a single
220 step. The -z flag to interdiff will even let y 223 step. The -z flag to interdiff will even let you feed it patches in gzip or
221 bzip2 compressed form directly without the use 224 bzip2 compressed form directly without the use of zcat or bzcat or manual
222 decompression. 225 decompression.
223 226
224 Here's how you'd go from 5.7.2 to 5.7.3 in a s !! 227 Here's how you'd go from 4.7.2 to 4.7.3 in a single step::
225 228
226 interdiff -z ../patch-5.7.2.gz ../patc !! 229 interdiff -z ../patch-4.7.2.gz ../patch-4.7.3.gz | patch -p1
227 230
228 Although interdiff may save you a step or two 231 Although interdiff may save you a step or two you are generally advised to
229 do the additional steps since interdiff can ge 232 do the additional steps since interdiff can get things wrong in some cases.
230 233
231 Another alternative is ``ketchup``, which is a 234 Another alternative is ``ketchup``, which is a python script for automatic
232 downloading and applying of patches (https://w !! 235 downloading and applying of patches (http://www.selenic.com/ketchup/).
233 236
234 Other nice tools are diffstat, which shows a s 237 Other nice tools are diffstat, which shows a summary of changes made by a
235 patch; lsdiff, which displays a short listing 238 patch; lsdiff, which displays a short listing of affected files in a patch
236 file, along with (optionally) the line numbers 239 file, along with (optionally) the line numbers of the start of each patch;
237 and grepdiff, which displays a list of the fil 240 and grepdiff, which displays a list of the files modified by a patch where
238 the patch contains a given regular expression. 241 the patch contains a given regular expression.
239 242
240 243
241 Where can I download the patches? 244 Where can I download the patches?
242 ================================= 245 =================================
243 246
244 The patches are available at https://kernel.or !! 247 The patches are available at http://kernel.org/
245 Most recent patches are linked from the front 248 Most recent patches are linked from the front page, but they also have
246 specific homes. 249 specific homes.
247 250
248 The 5.x.y (-stable) and 5.x patches live at !! 251 The 4.x.y (-stable) and 4.x patches live at
249 <<
250 https://www.kernel.org/pub/linux/kerne <<
251 <<
252 The 5.x.y incremental patches live at <<
253 <<
254 https://www.kernel.org/pub/linux/kerne <<
255 252
256 The -rc patches are not stored on the webserve !! 253 https://www.kernel.org/pub/linux/kernel/v4.x/
257 demand from git tags such as <<
258 254
259 https://git.kernel.org/torvalds/p/v5.1 !! 255 The -rc patches live at
260 256
261 The stable -rc patches live at !! 257 https://www.kernel.org/pub/linux/kernel/v4.x/testing/
262 258
263 https://www.kernel.org/pub/linux/kerne <<
264 259
265 !! 260 The 4.x kernels
266 The 5.x kernels <<
267 =============== 261 ===============
268 262
269 These are the base stable releases released by 263 These are the base stable releases released by Linus. The highest numbered
270 release is the most recent. 264 release is the most recent.
271 265
272 If regressions or other serious flaws are foun 266 If regressions or other serious flaws are found, then a -stable fix patch
273 will be released (see below) on top of this ba !! 267 will be released (see below) on top of this base. Once a new 4.x base
274 kernel is released, a patch is made available 268 kernel is released, a patch is made available that is a delta between the
275 previous 5.x kernel and the new one. !! 269 previous 4.x kernel and the new one.
276 270
277 To apply a patch moving from 5.6 to 5.7, you'd !! 271 To apply a patch moving from 4.6 to 4.7, you'd do the following (note
278 that such patches do **NOT** apply on top of 5 !! 272 that such patches do **NOT** apply on top of 4.x.y kernels but on top of the
279 base 5.x kernel -- if you need to move from 5. !! 273 base 4.x kernel -- if you need to move from 4.x.y to 4.x+1 you need to
280 first revert the 5.x.y patch). !! 274 first revert the 4.x.y patch).
281 275
282 Here are some examples:: 276 Here are some examples::
283 277
284 # moving from 5.6 to 5.7 !! 278 # moving from 4.6 to 4.7
285 279
286 $ cd ~/linux-5.6 # chan !! 280 $ cd ~/linux-4.6 # change to kernel source dir
287 $ patch -p1 < ../patch-5.7 # appl !! 281 $ patch -p1 < ../patch-4.7 # apply the 4.7 patch
288 $ cd .. 282 $ cd ..
289 $ mv linux-5.6 linux-5.7 # rena !! 283 $ mv linux-4.6 linux-4.7 # rename source dir
290 284
291 # moving from 5.6.1 to 5.7 !! 285 # moving from 4.6.1 to 4.7
292 286
293 $ cd ~/linux-5.6.1 # chan !! 287 $ cd ~/linux-4.6.1 # change to kernel source dir
294 $ patch -p1 -R < ../patch-5.6.1 # reve !! 288 $ patch -p1 -R < ../patch-4.6.1 # revert the 4.6.1 patch
295 # sour !! 289 # source dir is now 4.6
296 $ patch -p1 < ../patch-5.7 # appl !! 290 $ patch -p1 < ../patch-4.7 # apply new 4.7 patch
297 $ cd .. 291 $ cd ..
298 $ mv linux-5.6.1 linux-5.7 # rena !! 292 $ mv linux-4.6.1 linux-4.7 # rename source dir
299 293
300 294
301 The 5.x.y kernels !! 295 The 4.x.y kernels
302 ================= 296 =================
303 297
304 Kernels with 3-digit versions are -stable kern 298 Kernels with 3-digit versions are -stable kernels. They contain small(ish)
305 critical fixes for security problems or signif 299 critical fixes for security problems or significant regressions discovered
306 in a given 5.x kernel. !! 300 in a given 4.x kernel.
307 301
308 This is the recommended branch for users who w 302 This is the recommended branch for users who want the most recent stable
309 kernel and are not interested in helping test 303 kernel and are not interested in helping test development/experimental
310 versions. 304 versions.
311 305
312 If no 5.x.y kernel is available, then the high !! 306 If no 4.x.y kernel is available, then the highest numbered 4.x kernel is
313 the current stable kernel. 307 the current stable kernel.
314 308
315 The -stable team provides normal as well as in !! 309 .. note::
316 how to apply these patches. <<
317 <<
318 Normal patches <<
319 ~~~~~~~~~~~~~~ <<
320 310
321 These patches are not incremental, meaning tha !! 311 The -stable team usually do make incremental patches available as well
322 patch does not apply on top of the 5.7.2 kerne !! 312 as patches against the latest mainline release, but I only cover the
323 of the base 5.7 kernel source. !! 313 non-incremental ones below. The incremental ones can be found at
324 !! 314 https://www.kernel.org/pub/linux/kernel/v4.x/incr/
325 So, in order to apply the 5.7.3 patch to your !! 315
326 source you have to first back out the 5.7.2 pa !! 316 These patches are not incremental, meaning that for example the 4.7.3
327 base 5.7 kernel source) and then apply the new !! 317 patch does not apply on top of the 4.7.2 kernel source, but rather on top
>> 318 of the base 4.7 kernel source.
>> 319
>> 320 So, in order to apply the 4.7.3 patch to your existing 4.7.2 kernel
>> 321 source you have to first back out the 4.7.2 patch (so you are left with a
>> 322 base 4.7 kernel source) and then apply the new 4.7.3 patch.
328 323
329 Here's a small example:: 324 Here's a small example::
330 325
331 $ cd ~/linux-5.7.2 # chan !! 326 $ cd ~/linux-4.7.2 # change to the kernel source dir
332 $ patch -p1 -R < ../patch-5.7.2 # reve !! 327 $ patch -p1 -R < ../patch-4.7.2 # revert the 4.7.2 patch
333 $ patch -p1 < ../patch-5.7.3 # appl !! 328 $ patch -p1 < ../patch-4.7.3 # apply the new 4.7.3 patch
334 $ cd .. 329 $ cd ..
335 $ mv linux-5.7.2 linux-5.7.3 # rena !! 330 $ mv linux-4.7.2 linux-4.7.3 # rename the kernel source dir
336 <<
337 Incremental patches <<
338 ~~~~~~~~~~~~~~~~~~~ <<
339 <<
340 Incremental patches are different: instead of <<
341 of base 5.x kernel, they are applied on top of <<
342 (5.x.y-1). <<
343 <<
344 Here's the example to apply these:: <<
345 <<
346 $ cd ~/linux-5.7.2 # chan <<
347 $ patch -p1 < ../patch-5.7.2-3 # appl <<
348 $ cd .. <<
349 $ mv linux-5.7.2 linux-5.7.3 # rena <<
350 <<
351 331
352 The -rc kernels 332 The -rc kernels
353 =============== 333 ===============
354 334
355 These are release-candidate kernels. These are 335 These are release-candidate kernels. These are development kernels released
356 by Linus whenever he deems the current git (th 336 by Linus whenever he deems the current git (the kernel's source management
357 tool) tree to be in a reasonably sane state ad 337 tool) tree to be in a reasonably sane state adequate for testing.
358 338
359 These kernels are not stable and you should ex 339 These kernels are not stable and you should expect occasional breakage if
360 you intend to run them. This is however the mo 340 you intend to run them. This is however the most stable of the main
361 development branches and is also what will eve 341 development branches and is also what will eventually turn into the next
362 stable kernel, so it is important that it be t 342 stable kernel, so it is important that it be tested by as many people as
363 possible. 343 possible.
364 344
365 This is a good branch to run for people who wa 345 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 346 development kernels but do not want to run some of the really experimental
367 stuff (such people should see the sections abo !! 347 stuff (such people should see the sections about -git and -mm kernels below).
368 348
369 The -rc patches are not incremental, they appl !! 349 The -rc patches are not incremental, they apply to a base 4.x kernel, just
370 like the 5.x.y patches described above. The ke !! 350 like the 4.x.y patches described above. The kernel version before the -rcN
371 suffix denotes the version of the kernel that 351 suffix denotes the version of the kernel that this -rc kernel will eventually
372 turn into. 352 turn into.
373 353
374 So, 5.8-rc5 means that this is the fifth relea !! 354 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 !! 355 kernel and the patch should be applied on top of the 4.7 kernel source.
376 356
377 Here are 3 examples of how to apply these patc 357 Here are 3 examples of how to apply these patches::
378 358
379 # first an example of moving from 5.7 !! 359 # first an example of moving from 4.7 to 4.8-rc3
380 360
381 $ cd ~/linux-5.7 !! 361 $ cd ~/linux-4.7 # change to the 4.7 source dir
382 $ patch -p1 < ../patch-5.8-rc3 !! 362 $ patch -p1 < ../patch-4.8-rc3 # apply the 4.8-rc3 patch
383 $ cd .. 363 $ cd ..
384 $ mv linux-5.7 linux-5.8-rc3 !! 364 $ mv linux-4.7 linux-4.8-rc3 # rename the source dir
>> 365
>> 366 # now let's move from 4.8-rc3 to 4.8-rc5
>> 367
>> 368 $ cd ~/linux-4.8-rc3 # change to the 4.8-rc3 dir
>> 369 $ patch -p1 -R < ../patch-4.8-rc3 # revert the 4.8-rc3 patch
>> 370 $ patch -p1 < ../patch-4.8-rc5 # apply the new 4.8-rc5 patch
>> 371 $ cd ..
>> 372 $ mv linux-4.8-rc3 linux-4.8-rc5 # rename the source dir
>> 373
>> 374 # finally let's try and move from 4.7.3 to 4.8-rc5
>> 375
>> 376 $ cd ~/linux-4.7.3 # change to the kernel source dir
>> 377 $ patch -p1 -R < ../patch-4.7.3 # revert the 4.7.3 patch
>> 378 $ patch -p1 < ../patch-4.8-rc5 # apply new 4.8-rc5 patch
>> 379 $ cd ..
>> 380 $ mv linux-4.7.3 linux-4.8-rc5 # rename the kernel source dir
>> 381
>> 382
>> 383 The -git kernels
>> 384 ================
>> 385
>> 386 These are daily snapshots of Linus' kernel tree (managed in a git
>> 387 repository, hence the name).
>> 388
>> 389 These patches are usually released daily and represent the current state of
>> 390 Linus's tree. They are more experimental than -rc kernels since they are
>> 391 generated automatically without even a cursory glance to see if they are
>> 392 sane.
>> 393
>> 394 -git patches are not incremental and apply either to a base 4.x kernel or
>> 395 a base 4.x-rc kernel -- you can see which from their name.
>> 396 A patch named 4.7-git1 applies to the 4.7 kernel source and a patch
>> 397 named 4.8-rc3-git2 applies to the source of the 4.8-rc3 kernel.
>> 398
>> 399 Here are some examples of how to apply these patches::
385 400
386 # now let's move from 5.8-rc3 to 5.8-r !! 401 # moving from 4.7 to 4.7-git1
387 402
388 $ cd ~/linux-5.8-rc3 !! 403 $ cd ~/linux-4.7 # change to the kernel source dir
389 $ patch -p1 -R < ../patch-5.8-rc3 !! 404 $ patch -p1 < ../patch-4.7-git1 # apply the 4.7-git1 patch
390 $ patch -p1 < ../patch-5.8-rc5 <<
391 $ cd .. 405 $ cd ..
392 $ mv linux-5.8-rc3 linux-5.8-rc5 !! 406 $ mv linux-4.7 linux-4.7-git1 # rename the kernel source dir
393 407
394 # finally let's try and move from 5.7. !! 408 # moving from 4.7-git1 to 4.8-rc2-git3
395 409
396 $ cd ~/linux-5.7.3 !! 410 $ cd ~/linux-4.7-git1 # change to the kernel source dir
397 $ patch -p1 -R < ../patch-5.7.3 !! 411 $ patch -p1 -R < ../patch-4.7-git1 # revert the 4.7-git1 patch
398 $ patch -p1 < ../patch-5.8-rc5 !! 412 # we now have a 4.7 kernel
>> 413 $ patch -p1 < ../patch-4.8-rc2 # apply the 4.8-rc2 patch
>> 414 # the kernel is now 4.8-rc2
>> 415 $ patch -p1 < ../patch-4.8-rc2-git3 # apply the 4.8-rc2-git3 patch
>> 416 # the kernel is now 4.8-rc2-git3
399 $ cd .. 417 $ cd ..
400 $ mv linux-5.7.3 linux-5.8-rc5 !! 418 $ mv linux-4.7-git1 linux-4.8-rc2-git3 # rename source dir
401 419
402 420
403 The -mm patches and the linux-next tree 421 The -mm patches and the linux-next tree
404 ======================================= 422 =======================================
405 423
406 The -mm patches are experimental patches relea 424 The -mm patches are experimental patches released by Andrew Morton.
407 425
408 In the past, -mm tree were used to also test s 426 In the past, -mm tree were used to also test subsystem patches, but this
409 function is now done via the 427 function is now done via the
410 `linux-next` (https://www.kernel.org/doc/man-p !! 428 `linux-next <https://www.kernel.org/doc/man-pages/linux-next.html>`
411 tree. The Subsystem maintainers push their pat 429 tree. The Subsystem maintainers push their patches first to linux-next,
412 and, during the merge window, sends them direc 430 and, during the merge window, sends them directly to Linus.
413 431
414 The -mm patches serve as a sort of proving gro 432 The -mm patches serve as a sort of proving ground for new features and other
415 experimental patches that aren't merged via a 433 experimental patches that aren't merged via a subsystem tree.
416 Once such patches has proved its worth in -mm 434 Once such patches has proved its worth in -mm for a while Andrew pushes
417 it on to Linus for inclusion in mainline. 435 it on to Linus for inclusion in mainline.
418 436
419 The linux-next tree is daily updated, and incl 437 The linux-next tree is daily updated, and includes the -mm patches.
420 Both are in constant flux and contains many ex 438 Both are in constant flux and contains many experimental features, a
421 lot of debugging patches not appropriate for m 439 lot of debugging patches not appropriate for mainline etc., and is the most
422 experimental of the branches described in this 440 experimental of the branches described in this document.
423 441
424 These patches are not appropriate for use on s 442 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 443 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 444 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 445 even more so for -mm patches or using a Kernel from the linux-next tree).
428 446
429 Testing of -mm patches and linux-next is great 447 Testing of -mm patches and linux-next is greatly appreciated since the whole
430 point of those are to weed out regressions, cr 448 point of those are to weed out regressions, crashes, data corruption bugs,
431 build breakage (and any other bug in general) 449 build breakage (and any other bug in general) before changes are merged into
432 the more stable mainline Linus tree. 450 the more stable mainline Linus tree.
433 451
434 But testers of -mm and linux-next should be aw 452 But testers of -mm and linux-next should be aware that breakages are
435 more common than in any other tree. 453 more common than in any other tree.
436 454
437 455
438 This concludes this list of explanations of th 456 This concludes this list of explanations of the various kernel trees.
439 I hope you are now clear on how to apply the v 457 I hope you are now clear on how to apply the various patches and help testing
440 the kernel. 458 the kernel.
441 459
442 Thank you's to Randy Dunlap, Rolf Eike Beer, L 460 Thank you's to Randy Dunlap, Rolf Eike Beer, Linus Torvalds, Bodo Eggert,
443 Johannes Stezenbach, Grant Coady, Pavel Machek 461 Johannes Stezenbach, Grant Coady, Pavel Machek and others that I may have
444 forgotten for their reviews and contributions 462 forgotten for their reviews and contributions to this document.
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