Message-ID: <f7cb4209-a70f-4f59-8b11-2d189908f18c@t-8ch.de>
Date:   Fri, 2 Jun 2023 12:33:43 +0200
From:   Thomas Weißschuh <thomas@...ch.de>
To:     Zhangjin Wu <falcon@...ylab.org>
Cc:     arnd@...db.de, w@....eu, linux-kernel@...r.kernel.org,
        linux-kselftest@...r.kernel.org, linux-riscv@...ts.infradead.org
Subject: Re: [PATCH v2 13/13] selftests/nolibc: riscv: customize makefile for
 rv32

On 2023-06-02 12:06:25+0800, Zhangjin Wu wrote:
> Willy, Arnd and Thomas
> 
> Based on your suggestions, in the comming v3, I plan to split the whole rv32
> support to something like this:

Is each of these parts a new patchset?
I would suggest to do so.

> 1. Generic part1
> 
>    (The old feedbacks are applied with the new Suggested-by lines, welcome your
>     additional feedbacks if there are ;-))
> 
>     selftests/nolibc: syscall_args: use generic __NR_statx
>     tools/nolibc: add missing nanoseconds support for __NR_statx
>     selftests/nolibc: allow specify extra arguments for qemu
>     selftests/nolibc: fix up compile warning with glibc on x86_64
>     selftests/nolibc: not include limits.h for nolibc
>     selftests/nolibc: use INT_MAX instead of __INT_MAX__
>     tools/nolibc: arm: add missing my_syscall6
>     tools/nolibc: open: fix up compile warning for arm
>     selftests/nolibc: support two errnos with EXPECT_SYSER2()
>     selftests/nolibc: remove gettimeofday_bad1/2 completely
>     selftests/nolibc: add new gettimeofday test cases

These all look good and non-controversial.

> 2. Add Compile support for rv32
> 
>    (Convert all of the unsupported syscalls to a return of -ENOSYS, this
>     allows us to fix up the test failures one by one not that urgently later)
> 
>     tools/nolibc: fix up #error compile failures with -ENOSYS
>     tools/nolibc: fix up undeclared syscall macros with #ifdef and -ENOSYS

These should be their own series in my opinion.
It will likely generate some discussion.

>     selftests/nolibc: riscv: customize makefile for rv32
> 
>    (The first two are new but clear enough, based on the idea of suggestion from Arnd [1])
> 
> 3. Fix up the left test failures one by one

I'm not a fan of adding an "official" rv32 support with still failing
tests.

>    (Plan to add everyone as a standalone patchset, which will easier the review
>     and merge progress)
> 
>    wait4 -> waitid
>    lseek -> llseek
>    gettimeofday -> clock_gettime/clock_gettime64
>    select -> pselect6/pselect6_time64
>    ppoll -> ppoll_time64

I guess these new codepaths will also be used on non-rv32 architectures
and will therefore validated without rv32.

So you could submit these before the final rv32 patch in a series.

> 4. Clean up some old test cases one by one
> 
>    Like statx ...
> 
> Best regards,
> Zhangjin
> 
> [1]: https://lore.kernel.org/linux-riscv/5e7d2adf-e96f-41ca-a4c6-5c87a25d4c9c@app.fastmail.com/
> 
> > Both riscv64 and riscv32 have:
> > 
> > * the same ARCH value, it is riscv
> > * the same arch/riscv source code tree
> > 
> > The only differences are:
> > 
> > * riscv64 uses defconfig, riscv32 uses rv32_defconfig
> > * riscv64 uses qemu-system-riscv64, riscv32 uses qemu-system-riscv32
> > * riscv32 has different compiler options (-march= and -mabi=)
> > 
> > So, riscv32 can share most of the settings with riscv64, there is no
> > need to add it as a whole new architecture but just need a flag to
> > record and reflect the difference.
> > 
> > The 32bit mips and loongarch may be able to use the same method, so,
> > let's use a meaningful flag: CONFIG_32BIT. If required in the future,
> > this flag can also be automatically loaded from
> > include/config/auto.conf.
> > 
> > With this patch, it is able to run nolibc test for rv32 like this:
> > 
> >     $ make run ARCH=riscv32 CROSS_COMPILE=riscv64-linux-gnu- ...
> > 
> > Signed-off-by: Zhangjin Wu <falcon@...ylab.org>
> > ---
> >  tools/testing/selftests/nolibc/Makefile | 11 +++++++++--
> >  1 file changed, 9 insertions(+), 2 deletions(-)
> > 
> > diff --git a/tools/testing/selftests/nolibc/Makefile b/tools/testing/selftests/nolibc/Makefile
> > index 44088535682e..ea434a0acdc1 100644
> > --- a/tools/testing/selftests/nolibc/Makefile
> > +++ b/tools/testing/selftests/nolibc/Makefile
> > @@ -14,6 +14,12 @@ include $(srctree)/scripts/subarch.include
> >  ARCH = $(SUBARCH)
> >  endif
> >  
> > +# Allow pass ARCH=riscv|riscv32|riscv64, riscv implies riscv64
> > +ifneq ($(findstring xriscv,x$(ARCH)),)
> > +  CONFIG_32BIT := $(if $(findstring 32x,$(ARCH)x),1)
> > +  override ARCH := riscv
> > +endif
> > +
> >  # kernel image names by architecture
> >  IMAGE_i386       = arch/x86/boot/bzImage
> >  IMAGE_x86_64     = arch/x86/boot/bzImage
> > @@ -34,7 +40,7 @@ DEFCONFIG_x86        = defconfig
> >  DEFCONFIG_arm64      = defconfig
> >  DEFCONFIG_arm        = multi_v7_defconfig
> >  DEFCONFIG_mips       = malta_defconfig
> > -DEFCONFIG_riscv      = defconfig
> > +DEFCONFIG_riscv      = $(if $(CONFIG_32BIT),rv32_defconfig,defconfig)
> >  DEFCONFIG_s390       = defconfig
> >  DEFCONFIG_loongarch  = defconfig
> >  DEFCONFIG            = $(DEFCONFIG_$(ARCH))
> > @@ -49,7 +55,7 @@ QEMU_ARCH_x86        = x86_64
> >  QEMU_ARCH_arm64      = aarch64
> >  QEMU_ARCH_arm        = arm
> >  QEMU_ARCH_mips       = mipsel  # works with malta_defconfig
> > -QEMU_ARCH_riscv      = riscv64
> > +QEMU_ARCH_riscv      = $(if $(CONFIG_32BIT),riscv32,riscv64)
> >  QEMU_ARCH_s390       = s390x
> >  QEMU_ARCH_loongarch  = loongarch64
> >  QEMU_ARCH            = $(QEMU_ARCH_$(ARCH))
> > @@ -76,6 +82,7 @@ else
> >  Q=@
> >  endif
> >  
> > +CFLAGS_riscv = $(if $(CONFIG_32BIT),-march=rv32i -mabi=ilp32)
> >  CFLAGS_s390 = -m64
> >  CFLAGS_STACKPROTECTOR ?= $(call cc-option,-mstack-protector-guard=global $(call cc-option,-fstack-protector-all))
> >  CFLAGS  ?= -Os -fno-ident -fno-asynchronous-unwind-tables -std=c89 \
> > -- 
> > 2.25.1
> 

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