Re: [PATCH v1 2/3] selftests/nolibc: fix up O= option support

From: Willy Tarreau
Date: Fri Aug 04 2023 - 13:54:47 EST


On Fri, Aug 04, 2023 at 07:51:50PM +0200, Thomas Weißschuh wrote:
> On 2023-08-05 00:29:10+0800, Zhangjin Wu wrote:
> > > 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@xxxxxx>
> > > > > > > > Link: https://lore.kernel.org/lkml/ZK0AB1OXH1s2xYsh@xxxxxx/
> > > > > > > > Signed-off-by: Zhangjin Wu <falcon@xxxxxxxxxxx>
> > > > > > > > ---
> > > > > > > > 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?
>
> More like:
>
> - $(Q)qemu-system-$(QEMU_ARCH) -display none -no-reboot -kernel "$(srctree)/$(IMAGE)" -serial stdio $(QEMU_ARGS) > "$(CURDIR)/run.out"
> + $(Q)qemu-system-$(QEMU_ARCH) -display none -no-reboot -kernel "$(OUTPUT)$(IMAGE)" -serial stdio $(QEMU_ARGS) > "$(CURDIR)/run.out"
>
> My assumption was that it's weird that we need to define such variables
> ourselves.
>
> Using an empty $(OUTPUT) would have been fine if make is run from the
> root of the kernel tree. But that is not the case.
>
> It still feels weird but I can't think of a nicer way, and it's not
> a big issue. So let's keep that part the same.
>
> Or maybe Willy has a better idea.

I've just glanced over the discussion, but I'm wondering, why not
"$(objtree)/$(IMAGE)" instead ?

Willy