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From: Willy Tarreau <w@1wt.eu>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Zhangjin Wu <falcon@tinylab.org>,
	linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org,
	linux-riscv@lists.infradead.org,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	thomas@t-8ch.de
Subject: Re: [PATCH 04/13] selftests/nolibc: syscall_args: use __NR_statx for rv32
Date: Fri, 26 May 2023 12:06:24 +0200	[thread overview]
Message-ID: <ZHCEoKXHSDlDvI5u@1wt.eu> (raw)
In-Reply-To: <ee8b1f02-ded1-488b-a3a5-68774f0349b5@app.fastmail.com>

Hi Arnd,

On Fri, May 26, 2023 at 11:21:02AM +0200, Arnd Bergmann wrote:
> On Wed, May 24, 2023, at 19:48, Zhangjin Wu wrote:
> 
> > 
> > +static int test_syscall_args(void)
> > +{
> > +#ifdef __NR_fstat
> > +	return syscall(__NR_fstat, 0, NULL);
> > +#elif defined(__NR_statx)
> > +	return syscall(__NR_statx, 0, NULL, 0, 0, NULL);
> > +#else
> > +#error Neither __NR_fstat nor __NR_statx defined, cannot implement 
> > syscall_args test
> > +#endif
> > +}
> 
> Does this need to work on old kernels? My impression was that
> this is only intended to be used with the kernel that ships the
> copy, so you can just rely on statx to be defined and drop
> the old fallbacks (same as for pselect6_time64 as I commented).

Yes, as much as possible this is desirable because the purpose is
clearly to simplify the build of applications. The reason is that
some applications might want to run as well on older kernels, but
may miss some syscalls on the nolibc shipped with these older ones.
Since the project is quite young, it lags a lot behind what each
kernel supports, so it's expected that users will take the most
recent nolibc version to benefit from support of syscalls that were
already present in older ones.

The alternative would be to take the project out of the kernel as it
was before but this would likely complicate contributions.

However the selftest code is clearly specific to a kernel IMHO, since
its goal is to be used to check that the shipped version of nolibc works
on this kernel.

As such, my view on this is that as long as it doesn't require
unreasonable efforts to support older kernels for the userland code,
we should try. If sometimes it's a big pain, we should not insist too
much, but at least making sure that only the feature in question will
not work would be desirable.

Thanks,
Willy

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  reply	other threads:[~2023-05-26 10:12 UTC|newest]

Thread overview: 60+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-05-24 17:33 [PATCH 00/13] tools/nolibc: riscv: Add full rv32 support Zhangjin Wu
2023-05-24 17:41 ` [PATCH 01/13] Revert "tools/nolibc: riscv: Support __NR_llseek for rv32" Zhangjin Wu
2023-05-24 17:44 ` [PATCH 02/13] Revert "selftests/nolibc: Fix up compile error " Zhangjin Wu
2023-05-24 17:48 ` [PATCH 04/13] selftests/nolibc: syscall_args: use __NR_statx for rv32 Zhangjin Wu
2023-05-24 19:49   ` Thomas Weißschuh
2023-05-25  7:20     ` Zhangjin Wu
2023-05-26  9:21   ` Arnd Bergmann
2023-05-26 10:06     ` Willy Tarreau [this message]
2023-05-27  0:58     ` Zhangjin Wu
2023-05-24 17:50 ` [PATCH 05/13] selftests/nolibc: riscv: customize makefile " Zhangjin Wu
2023-05-26  6:57   ` Thomas Weißschuh
2023-05-26  9:20     ` Zhangjin Wu
2023-05-24 17:52 ` [PATCH 06/13] selftests/nolibc: allow specify a bios for qemu Zhangjin Wu
2023-05-26  7:00   ` Thomas Weißschuh
2023-05-26 10:25     ` Zhangjin Wu
2023-05-26 10:36       ` Conor Dooley
2023-05-26 13:38         ` Zhangjin Wu
2023-05-26 15:08           ` Conor Dooley
2023-05-28  7:52     ` Willy Tarreau
2023-05-24 17:54 ` [PATCH 07/13] selftests/nolibc: remove the duplicated gettimeofday_bad2 Zhangjin Wu
2023-05-24 17:55 ` [PATCH 08/13] tools/nolibc: sys_lseek: riscv: use __NR_llseek for rv32 Zhangjin Wu
2023-05-24 17:57 ` [PATCH 09/13] tools/nolibc: sys_poll: riscv: use __NR_ppoll_time64 " Zhangjin Wu
2023-05-26  7:15   ` Thomas Weißschuh
2023-05-26  9:34     ` Arnd Bergmann
2023-05-28  8:25       ` Zhangjin Wu
2023-05-28  8:48         ` Arnd Bergmann
2023-05-28 10:29         ` Willy Tarreau
2023-05-28 10:55           ` Arnd Bergmann
2023-05-28 11:03             ` Willy Tarreau
2023-05-24 17:58 ` [PATCH 10/13] tools/nolibc: ppoll/ppoll_time64: add a missing argument Zhangjin Wu
2023-05-24 17:59 ` [PATCH 11/13] tools/nolibc: sys_select: riscv: use __NR_pselect6_time64 for rv32 Zhangjin Wu
2023-05-24 20:22   ` Thomas Weißschuh
2023-05-25  7:10     ` Zhangjin Wu
2023-05-25  7:22       ` Thomas Weißschuh
2023-05-26  1:50         ` Zhangjin Wu
2023-05-26  9:19   ` Arnd Bergmann
2023-05-26 11:00     ` [PATCH 00/13] tools/nolibc: riscv: Add full rv32 support Zhangjin Wu
2023-05-26 11:13       ` Arnd Bergmann
2023-05-24 18:02 ` [PATCH 12/13] tools/nolibc: sys_wait4: riscv: use __NR_waitid for rv32 Zhangjin Wu
2023-05-24 18:03 ` [PATCH 13/13] tools/nolibc: sys_gettimeofday: riscv: use __NR_clock_gettime64 " Zhangjin Wu
2023-05-26  7:38   ` Thomas Weißschuh
2023-05-27  1:26     ` Zhangjin Wu
2023-05-27  3:39       ` Zhangjin Wu
2023-05-27  5:12       ` Willy Tarreau
2023-05-24 18:24 ` [PATCH 00/13] tools/nolibc: riscv: Add full rv32 support Zhangjin Wu
2023-05-24 18:28 ` [PATCH 03/13] selftests/nolibc: print name instead of number for EOVERFLOW Zhangjin Wu
2023-05-24 17:46   ` Zhangjin Wu
2023-05-24 20:23   ` Thomas Weißschuh
2023-05-28  7:59 ` [PATCH 00/13] tools/nolibc: riscv: Add full rv32 support Willy Tarreau
2023-05-28  8:42   ` Thomas Weißschuh
2023-05-28  9:41     ` Thomas Weißschuh
2023-05-28 10:17       ` Willy Tarreau
2023-05-28 10:39   ` Zhangjin Wu
2023-05-28 11:33     ` Willy Tarreau
2023-05-28 12:52       ` Zhangjin Wu
2023-05-28 13:45     ` Thomas Weißschuh 
2023-05-28 18:39       ` Zhangjin Wu
2023-05-29  8:45         ` Thomas Weißschuh
2023-05-29 11:31           ` Willy Tarreau
2023-05-30 10:06             ` Zhangjin Wu

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