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Re: [RFC PATCH v2] Linux/Alpha: don't use timeval32 system calls.
- From: Zack Weinberg <zackw at panix dot com>
- To: Arnd Bergmann <arnd at arndb dot de>
- Cc: GNU C Library <libc-alpha at sourceware dot org>, Joseph Myers <joseph at codesourcery dot com>, Florian Weimer <fweimer at redhat dot com>, Lukasz Majewski <lukma at denx dot de>, Alistair Francis <alistair23 at gmail dot com>, Stepan Golosunov <stepan at golosunov dot pp dot ru>, Adhemerval Zanella <adhemerval dot zanella at linaro dot org>, Richard Henderson <rth at twiddle dot net>
- Date: Thu, 29 Aug 2019 13:57:33 -0400
- Subject: Re: [RFC PATCH v2] Linux/Alpha: don't use timeval32 system calls.
- References: <20190828153043.23644-1-zackw@panix.com> <CAK8P3a3oHbhRg4kSi1DMeNPMm4Ehev+kn+5NvDKANbJeppGjiQ@mail.gmail.com>
On Wed, Aug 28, 2019 at 11:58 AM Arnd Bergmann <arnd@arndb.de> wrote:
> On Wed, Aug 28, 2019 at 5:30 PM Zack Weinberg <zackw@panix.com> wrote:
> >
> > * The patched glibc will NOT use system calls that involve 32-bit
> > time_t to implement its compatibility symbols. This will make both
> > our lives and the kernel maintainers' lives easier. The primary
> > argument I've seen against it is that the kernel could warn about
> > uses of the old system calls, helping people find old binaries that
> > need to be recompiled. I think there are several other ways we
> > could accomplish this, e.g. scripts to scan the filesystem for
> > binaries with references to the old symbol versions, or issuing
> > diagnostics ourselves.
>
> Another possible issue is seccomp filtering for a known set of
> syscalls. The kernel vdso just got reverted so it no longer falls
> back to the clock_gettime64() syscall to implement the
> clock_gettime() vdso call when that is unavailable
Yes, I'm aware that this is potentially a problem. In this specific
case, recompiling the program with 64-bit time_t (however that's
accomplished) would cause the program to change the set of syscalls it
uses and the seccomp filter to break _anyway_, so I think it's an
acceptable compatibility break.
zw