[RFC PATCH v2] Linux/Alpha: don't use timeval32 system calls.

[Zack Weinberg]

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