Today learned some things about git and applying patches. First when applying my trec/ace/kshmem patches to 2.6.25-rc2 they wouldn’t apply because now there only an x86 architecture (arch/x86) instead of two architectures i386 and x86_64. That was to be expected actually and there’s going to be some hand work in doing that.
To do this hand work I really need to see what my current patches look like and there isn’t quite enough context in the patch file to do that, at least for me. So I cloned the current linux-2.6 tree into a new directory linux-2.6-x and did a checkout of 2.6.21-rc6 which is what my patches should apply against.
Well almost, there was still some need for a little tweaking; First git am will take my series of patches which were generated using git format-patch and apply them extracting from the email the commit message and the patch. It then creates a commit. But if there is a problem in a series only those that applied cleanly will be committed.
The first patch that fails won’t be applied at all, for example:
error: patch failed: mm/vmalloc.c:469 error: mm/vmalloc.c: patch does not apply Patch failed at 0002. When you have resolved this problem run "git-am --resolved". If you would prefer to skip this patch, instead run "git-am --skip".
At this point I was scratching my head Patch failed at 0002 and when its resolved I can say so, but how to resolve it if its not been applied to the working tree. The solution is to use “git apply”:
git apply --reject --whitespace=fix my-patches/ace2-2.6.21-rc6/0002.patch
By using “git apply” with the –reject it will apply the patch leaving bad files with “xxx.rej” in my case mm/Kconfig.rej was the culprit. I resolved the problem with mm/Kconfig. Next I tried “git am –resolved”:
wink@ic2d1:$ git am --resolved Applying ACE implementation, conifguration and makefile No changes - did you forget to use 'git add'? When you have resolved this problem run "git-am --resolved". If you would prefer to skip this patch, instead run "git-am --skip"
More head scratching, “did you forget to use ‘git add’?” …. hm Ok so I then used “git gui” to add the files (BUT DID NOT DO A COMMIT) and then did “git am –resolved”:
wink@ic2d1:$ git am --resolved Applying ACE implementation, conifguration and makefile Applying ACE modifications to actually use ACE .dotest/patch:32: trailing whitespace. warning: 1 line adds whitespace errors. Applying ACE simple test program .dotest/patch:130: space before tab in indent. result ? "true" : "false", i); .dotest/patch:138: space before tab in indent. result ? "true" : "false", i); .dotest/patch:146: space before tab in indent. result ? "true" : "false", i); .dotest/patch:233: trailing whitespace. warning: 4 lines add whitespace errors.
That did it, so no commit was necessary, the “git am –resolved” did the commit and then continued with the other patches. Lean something new everyday!
文本来源：http://www.winksaville.com/blog/linux/git-applying-patches/