linux-kernel - Re: [PATCH] kbuild: use ARCH from compile.h in unclean source tree msg

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Message-ID: <0d27886e-5a3c-4073-a044-f6684de8333d@linuxfoundation.org>
Date: Tue, 6 May 2025 16:07:36 -0600
From: Shuah Khan <skhan@...uxfoundation.org>
To: Nicolas Schier <nicolas.schier@...ux.dev>
Cc: masahiroy@...nel.org, nathan@...nel.org, brendan.higgins@...ux.dev,
 davidgow@...gle.com, rmoar@...gle.com, linux-kbuild@...r.kernel.org,
 linux-kernel@...r.kernel.org, kunit-dev@...glegroups.com,
 linux-kselftest@...r.kernel.org, Shuah Khan <skhan@...uxfoundation.org>
Subject: Re: [PATCH] kbuild: use ARCH from compile.h in unclean source tree
 msg

On 5/6/25 05:12, Nicolas Schier wrote:
> On Fri, 02 May 2025, Shuah Khan wrote:
> 
>> When make finds the source tree unclean, it prints a message to run
>> "make ARCH=x86_64 mrproper" message using the ARCH from the command
>> line. The ARCH specified in the command line could be different from
>> the ARCH of the existing build in the source tree.
>>
>> This could cause problems in regular kernel build and kunit workflows.
>>
>> Regular workflow:
>>
>> - Build x86_64 kernel
>> 	$ make ARCH=x86_64
>> - Try building another arch kernel out of tree with O=
>> 	$ make ARCH=um O=/linux/build
>> - kbuild detects source tree is unclean
>>
>>    ***
>>    *** The source tree is not clean, please run 'make ARCH=um mrproper'
>>    *** in /linux/linux_srcdir
>>    ***
>>
>> - Clean source tree as suggested by kbuild
>> 	$ make ARCH=um mrproper
>> - Source clean appears to be clean, but it leaves behind generated header
>>    files under arch/x86
>>   	arch/x86/realmode/rm/pasyms.h
>>
>> A subsequent x86_64e build fails with
>>    "undefined symbol sev_es_trampoline_start referenced ..."
>>
>> kunit workflow runs into this issue:
>>
>> - Build x86_64 kernel
>> - Run kunit tests:  it tries to build for user specified ARCH or uml
>>    as default:
>> 	$ ./tools/testing/kunit/kunit.py run
>>
>> - kbuild detects unclean source tree
>>
>>    ***
>>    *** The source tree is not clean, please run 'make ARCH=um mrproper'
>>    *** in /linux/linux_6.15
>>    ***
>>
>> - Clean source tree as suggested by kbuild
>> 	$ make ARCH=um mrproper
>> - Source clean appears to be clean, but it leaves behind generated header
>>    files under arch/x86
>>
>> The problem shows when user tries to run tests on ARCH=x86_64:
>>
>> 	$ ./tools/testing/kunit/kunit.py run ARCH=x86_64
>>
>> 	"undefined symbol sev_es_trampoline_start referenced ..."
>>
>> Build trips on arch/x86/realmode/rm/pasyms.h left behind by a prior
>> x86_64 build.
>>
>> Problems related to partially cleaned source tree are hard to debug.
>> Change Makefile to unclean source logic to use ARCH from compile.h
>> UTS_MACHINE string. With this change kbuild prints:
>>
>> 	$ ./tools/testing/kunit/kunit.py run
>>
>>    ***
>>    *** The source tree is not clean, please run 'make ARCH=x86_64 mrproper'
>>    *** in /linux/linux_6.15
>>    ***
>>
>> Signed-off-by: Shuah Khan <skhan@...uxfoundation.org>
>> ---
>>   Makefile | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/Makefile b/Makefile
>> index 5aa9ee52a765..7ee29136b4da 100644
>> --- a/Makefile
>> +++ b/Makefile
>> @@ -674,7 +674,7 @@ ifeq ($(KBUILD_EXTMOD),)
>>   		 -d $(srctree)/include/config -o \
>>   		 -d $(srctree)/arch/$(SRCARCH)/include/generated ]; then \

Would it make sense to check for include/generated as a catch all?

>>   		echo >&2 "***"; \
>> -		echo >&2 "*** The source tree is not clean, please run 'make$(if $(findstring command line, $(origin ARCH)), ARCH=$(ARCH)) mrproper'"; \
>> +		echo >&2 "*** The source tree is not clean, please run 'make ARCH=$(shell grep UTS_MACHINE $(srctree)/include/generated/compile.h | cut -d '"' -f 2) mrproper'"; \
> 
> Please 'grep' option '-s'.
> 
> There are some (rare) occassions, when there is no include/generated/compile.h
> but still the source tree will be considered to be dirty:

I considered adding a check for not finding include/generated/compile.h
and figured if include/config is found we are probably safe.

I will fix that.

> 
>      grep: ../include/generated/compile.h: No such file or directory
>      ***
>      *** The source tree is not clean, please run 'make ARCH= mrproper'
>      ...
> 

thanks,
-- Shuah