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From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Fri, 24 Feb 2023 15:22:58 -0800
Message-ID: <CAHk-=wiEf7irTKwPJ0jTMOF3CS-13UXmF6Fns3wuWpOZ_wGyZQ@mail.gmail.com>
Subject: Re: [GIT PULL] KUnit next update for Linux 6.3-rc1
To:     Shuah Khan <skhan@linuxfoundation.org>
Cc:     shuah <shuah@kernel.org>, David Gow <davidgow@google.com>,
        Brendan Higgins <brendanhiggins@google.com>,
        linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org
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On Tue, Feb 21, 2023 at 5:51 PM Shuah Khan <skhan@linuxfoundation.org> wrote:
>
> This KUnit update for Linux 6.3-rc1 consists of cleanups, new features,
> and documentation updates:

Hmm. I have not actually bisected this or tried to otherwise figure
out exactly what is wrong, but the kunit code ends up being really
annoying for my build testing.

In particular, if I do

     make

repeatedly - ie with no other changes in between - the kunit code ends
up re-building itself for no apparent reason.

Which then causes a re-link and makes it all really slow.

Maybe I'm barking up the wrong tree, but just do

   make allmodconfig

and then do two plain "make"s in succession (feel free to add "-jXYZ"
to make it go much faster ;).

The second build - that shouldn't have to re-build anything - still does this:

  CALL    scripts/checksyscalls.sh
  DESCEND objtool
  CHK     kernel/kheaders_data.tar.xz
  CC      lib/kunit/hooks.o
  AR      lib/built-in.a
  CC      lib/kunit/hooks.o
  AR      lib/kunit/lib.a
  AR      built-in.a
  AR      vmlinux.a
  LD      vmlinux.o
  ...

and it all takes much longer than an empty kernel build _should_ take.

               Linus