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From:   Zhangjin Wu <falcon@tinylab.org>
To:     thomas@t-8ch.de
Cc:     arnd@arndb.de, falcon@tinylab.org, linux-kernel@vger.kernel.org,
        linux-kselftest@vger.kernel.org, tanyuan@tinylab.org, w@1wt.eu
Subject: Re: [PATCH v1 2/3] selftests/nolibc: fix up O= option support
Date:   Sat,  5 Aug 2023 00:29:10 +0800
Message-Id: <20230804162910.305533-1-falcon@tinylab.org>
In-Reply-To: <500504f6-fed1-45a4-a518-4631a6f3e463@t-8ch.de>
References: <500504f6-fed1-45a4-a518-4631a6f3e463@t-8ch.de>
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> On 2023-08-04 23:52:18+0800, Zhangjin Wu wrote:
> > > On 2023-08-04 15:43:42+0800, Zhangjin Wu wrote:
> > > > Hi, Thomas
> > > > 
> > > > > On 2023-08-03 22:45:52+0800, Zhangjin Wu wrote:
> > > > > > To avoid pollute the source code tree and avoid mrproper for every
> > > > > > architecture switch, the O= argument must be supported.
> > > > > > 
> > > > > > Both IMAGE and .config are from the building directory, let's use
> > > > > > objtree instead of srctree for them.
> > > > > > 
> > > > > > If no O= option specified, means building kernel in source code tree,
> > > > > > objtree should be srctree in such case.
> > > > > > 
> > > > > > Suggested-by: Willy Tarreau <w@1wt.eu>
> > > > > > Link: https://lore.kernel.org/lkml/ZK0AB1OXH1s2xYsh@1wt.eu/
> > > > > > Signed-off-by: Zhangjin Wu <falcon@tinylab.org>
> > > > > > ---
> > > > > >  tools/testing/selftests/nolibc/Makefile | 7 +++++--
> > > > > >  1 file changed, 5 insertions(+), 2 deletions(-)
> > > > > > 
> > > > > > diff --git a/tools/testing/selftests/nolibc/Makefile b/tools/testing/selftests/nolibc/Makefile
> > > > > > index 51fef5e6a152..af590aee063a 100644
> > > > > > --- a/tools/testing/selftests/nolibc/Makefile
> > > > > > +++ b/tools/testing/selftests/nolibc/Makefile
> > > > > > @@ -9,6 +9,9 @@ ifeq ($(srctree),)
> > > > > >  srctree := $(patsubst %/tools/testing/selftests/,%,$(dir $(CURDIR)))
> > > > > >  endif
> > > > > >  
> > > > > > +# add objtree for O= argument, required by IMAGE and .config
> > > > > > +objtree ?= $(srctree)
> > > > > 
> > > > > Isn't this already set by the included tools/scripts/Makefile.include?
> > > > >
> > > > 
> > > > Good question, but it is empty if no O= specified, checked it several
> > > > times before ;-)
> > > 
> > > For me it is not empty when I am in tools/testing/selftests/nolibc/.
> > >
> > 
> > Interesting, here is the code I added to check the value:
> > 
> >     diff --git a/tools/testing/selftests/nolibc/Makefile b/tools/testing/selftests/nolibc/Makefile
> >     index 22f1e1d73fa8..1ae19e896e24 100644
> >     --- a/tools/testing/selftests/nolibc/Makefile
> >     +++ b/tools/testing/selftests/nolibc/Makefile
> >     @@ -12,6 +12,8 @@ include $(srctree)/scripts/subarch.include
> >      ARCH = $(SUBARCH)
> >      endif
> >     
> >     +$(error objtree=$(objtree), srctree=$(srctree))
> >     +
> > 
> > Whenever I do defconfig or run,
> > 
> >     $ make help
> >     Makefile:15: *** objtree=, srctree=/labs/linux-lab/src/linux-stable.  Stop.
> > 
> > It is only not empty when we pass O explicitly:
> > 
> >     $ mkdir out
> >     $ make help O=out
> >     Makefile:15: *** objtree=out, srctree=/labs/linux-lab/src/linux-stable.  Stop.
> >     $ make help O=$PWD/out
> >     Makefile:15: *** objtree=/labs/linux-lab/src/linux-stable/tools/testing/selftests/nolibc/out, srctree=/labs/linux-lab/src/linux-stable.  Stop.
> 
> Welp, now it's the same for me.
> I guess I messed it up before, maybe I forgot to remove your changes
> while testing?
> 
> Anyways instead of having to manually do stuff with $(objtree) we could
> also use $(OUTPUT)$(IMAGE) to always get the correct image.
>

Do you mean here?

    # kernel image names by architecture
    IMAGE_i386    = arch/x86/boot/bzImage
    IMAGE_x86     = arch/x86/boot/bzImage
    IMAGE_arm64   = arch/arm64/boot/Image
    IMAGE_arm     = arch/arm/boot/zImage
    IMAGE_mips    = vmlinuz
    IMAGE_riscv   = arch/riscv/boot/Image
    IMAGE         = $(IMAGE_$(ARCH))
    IMAGE_NAME    = $(notdir $(IMAGE))

It does save another KERNEL_IMAGE macro in my future patch ;-)

But without O=, OUTPUT is also empty like objtree and when empty, it is
assigned as $(CURDIR), not $(srctree) as we expected for IMAGE and .config. To
be cleaner, objtree should also be used:

    - IMAGE         = $(IMAGE_$(ARCH))
    + IMAGE         = $(objtree)/$(IMAGE_$(ARCH))

Is this what you want?

Thanks!
Zhangjin

> > [..]
> > 
> > After align the empty objtree value with you, will renew this patch.
> 
> Thanks!
> Thomas