Messages in this thread | | | From | Ard Biesheuvel <> | Date | Thu, 8 Mar 2018 07:02:49 +0000 | Subject | Re: arm crypto .S_shipped files sometimes get rebuilt randomly |
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On 8 March 2018 at 05:00, Masahiro Yamada <yamada.masahiro@socionext.com> wrote: > 2018-03-08 4:25 GMT+09:00 Leonard Crestez <leonard.crestez@nxp.com>: >> Hello, >> >> I am using a toolchain with a broken/old version of perl which doesn't >> include integer.pm and I noticed it triggers occasional build failures >> on arch/arm64/crypto/sha512-core.S_shipped. Workarounds are easy, but >> if the purpose of the .S_shipped is to avoid the need to have all >> dependencies on the build machine then something went wrong? >> >> This was introduced by commit 7918ecef073f ("crypto: arm64/sha2 - >> integrate OpenSSL implementations of SHA256/SHA512"). The makefile >> rules are not terribly complicated: >> >> quiet_cmd_perlasm = PERLASM $@ >> cmd_perlasm = $(PERL) $(<) void $(@) >> >> $(src)/sha512-core.S_shipped: $(src)/sha512-armv8.pl >> $(call cmd,perlasm) >> >> If a decision to rerun the rule is made based on their relative >> timestamps but both .S_shipped and sha512-armv8.pl are included in git >> then won't the result be essentially random, depending on file checkout >> order? >>
I agree with your analysis, although I never see these spurious rebuilds of these files.
>> I see random success/failure by just running something like the >> following multiple times: >> rm -rf arch/arm64/crypto >> git co -f arch/arm64/crypto >> make -- arch/arm64/crypto/ >> >> A reasonable fix might be to simply drop .S_shipped and require a >> functional recent version of perl. Then if it fails it will fail >> reliably. >> > > Indeed, this Makefile is weird. > We have two choices. > > > [1] If we intend to generate > sha{256,512}-core.S from the perl script during the build, > this should be: > > $(obj)/sha512-core.S: $(src)/sha512-armv8.pl > $(call cmd,perlasm) > > $(obj)/sha512-core.S: $(src)/sha512-armv8.pl > $(call cmd,perlasm) > > > [2] If we want to check-in _shipped files > and avoid running perl during the build, > we can surround unnecessary rules with if-conditional, like > > > if REGENERATE_ARM64_SHA > $(src)/sha256-core.S_shipped: $(src)/sha512-armv8.pl > $(call cmd,perlasm) > > $(src)/sha512-core.S_shipped: $(src)/sha512-armv8.pl > $(call cmd,perlasm) > endif > > > Set REGENERATE_ARM64_SHA=1 from the command line > only when you need to update the _shipped files. > > This is what commit 7373f4f83c71d50f0aece6d94309ab7fde42180f did. > > > > > Recently, Kconfig switched to [1]. > So, flex and bison are required to build the kernel. >
I would prefer option [1], but only if it is already documented somewhere that Perl is a build time dependency.
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