linux-kernel - Re: [PATCH] um: let 'make clean' properly clean underlying SUBARCH as well

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Message-ID: <CAMuHMdVuQNi02KTCKnsS6V=POsz9X=2003b+CWxwCc=23ULuYQ@mail.gmail.com>
Date: Thu, 8 May 2025 10:17:04 +0200
From: Geert Uytterhoeven <geert@...ux-m68k.org>
To: Masahiro Yamada <masahiroy@...nel.org>
Cc: Johannes Berg <johannes@...solutions.net>, Shuah Khan <skhan@...uxfoundation.org>, 
	linux-kbuild@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Anton Ivanov <anton.ivanov@...bridgegreys.com>, Richard Weinberger <richard@....at>, 
	linux-um@...ts.infradead.org, David Gow <davidgow@...gle.com>
Subject: Re: [PATCH] um: let 'make clean' properly clean underlying SUBARCH as well

Hi Yamada-san,

On Thu, 8 May 2025 at 10:14, Masahiro Yamada <masahiroy@...nel.org> wrote:
> On Thu, May 8, 2025 at 4:38 PM Geert Uytterhoeven <geert@...ux-m68k.org> wrote:
> > On Thu, 8 May 2025 at 07:29, Johannes Berg <johannes@...solutions.net> wrote:
> > > On Wed, 2025-05-07 at 15:38 -0600, Shuah Khan wrote:
> > > > My workflow:
> > > >
> > > > - Build kernel on x86_64 with CONFIG_AMD_MEM_ENCRYPT enabled
> > > >
> > > > - Check for arch/x86/realmode/rm/pasyms.h
> > > >    ls arch/x86/realmode/rm/pasyms.h
> > > >       arch/x86/realmode/rm/pasyms.h
> > > >
> > > > - make ARCH=um O=/linux/build
> > > >
> > > >    This patch cleans the source tree, but doesn't remove
> > > >    arch/x86/realmode/rm/pasyms.h
> > > >
> > > > - ls arch/x86/realmode/rm/pasyms.h
> > > >       arch/x86/realmode/rm/pasyms.h
> > >
> > > Is that even _expected_ to work? If you have x86 built first, I'd almost
> > > expect you to have to do "make ARCH=x86 mrproper" before building
> > > another ARCH. I don't see how ARCH=um would know how to do a full clean
> > > up of ARCH=x86, unless this is somehow arch-independent?
> > >
> > > Or maybe that's not an issue with other architectures because UML is
> > > special in that it uses parts of x86?
> >
> > Probably.
> > I only use my linux-next source tree for fixing reported build issues on
> > various architectures, and I never use make clean/mrproper.  Works fine.
> >
> > > Though I guess the patch here should make it do that, more or less, but
> > > it can't, likely because you're also switching from in-tree build to O=
> > > build?
> >
> > Yeah, mixing in-tree and out-of-tree builds causes issues.
> > Never build in-tree in a source tree you use with O= (except for
> > e.g. "make tags").
>
> I argue this.
>
> You can start out-of-tree builds after running 'make mrproper'
> for the architecture you want to build the kernel for.
>
> Hence, Kbuild suggests to do so when it determines
> the source tree is not clean enough.

Sorry, I meant "without mrproper" (which wipes my tags file).

> Unfortunately, "make mrproper ARCH=um" did not clean the tree
> deeply enough.   Hence, this patch.

Thanks, fine!

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds