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Subject: Re: [PATCH] LoongArch: Define __ARCH_WANT_NEW_STAT in unistd.h
From: Xi Ruoyao <xry111@xry111.site>
To: Huacai Chen <chenhuacai@kernel.org>, Arnd Bergmann <arnd@arndb.de>
Cc: Huacai Chen <chenhuacai@loongson.cn>, loongarch@lists.linux.dev,
 Linux-Arch <linux-arch@vger.kernel.org>, Xuefeng Li
 <lixuefeng@loongson.cn>, guoren <guoren@kernel.org>, WANG Xuerui
 <kernel@xen0n.name>, Jiaxun Yang <jiaxun.yang@flygoat.com>,
 linux-kernel@vger.kernel.org,  loongson-kernel@lists.loongnix.cn,
 stable@vger.kernel.org
Date: Sat, 15 Jun 2024 16:55:08 +0800
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On Sat, 2024-06-15 at 16:52 +0800, Huacai Chen wrote:
> Hi, Arnd,
>=20
> On Sun, May 12, 2024 at 3:53=E2=80=AFPM Arnd Bergmann <arnd@arndb.de> wro=
te:
> >=20
> > On Sun, May 12, 2024, at 05:11, Huacai Chen wrote:
> > > On Sat, May 11, 2024 at 11:39=E2=80=AFPM Arnd Bergmann <arnd@arndb.de=
> wrote:
> > > > On Sat, May 11, 2024, at 16:28, Huacai Chen wrote:
> > > > > On Sat, May 11, 2024 at 8:17=E2=80=AFPM Arnd Bergmann <arnd@arndb=
.de> wrote:
> > > > CONFIG_COMPAT_32BIT_TIME is equally affected here. On riscv32
> > > > this is the only allowed configuration, while on others (arm32
> > > > or x86-32 userland) you can turn off COMPAT_32BIT_TIME on
> > > > both 32-bit kernel and on 64-bit kernels with compat mode.
> > > I don't know too much detail, but I think riscv32 can do something
> > > similar to arm32 and x86-32, or we can wait for Xuerui to improve
> > > seccomp. But there is no much time for loongarch because the Debian
> > > loong64 port is coming soon.
> >=20
> > What I meant is that the other architectures only work by
> > accident if COMPAT_32BIT_TIME is enabled and statx() gets
> > blocked, but then they truncate the timestamps to the tim32
> > range, which is not acceptable behavior. Actually mips64 is
> > in the same situation because it also only supports 32-bit
> > timestamps in newstatat(), despite being a 64-bit
> > architecture with a 64-bit time_t in all other syscalls.
> We can only wait for the seccomp side to be fixed now? Or we can get
> this patch upstream for LoongArch64 at the moment, and wait for
> seccomp to fix RISCV32 (and LoongArch32) in future?

I'm wondering why not just introduce a new syscall or extend statx with
a new flag, as we've discussed many times.  They have their own
disadvantages but better than this, IMO.

--=20
Xi Ruoyao <xry111@xry111.site>
School of Aerospace Science and Technology, Xidian University