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Re: [RFC v2 08/20] sysdeps/wait: Use waitid if avaliable
- From: Alistair Francis <alistair23 at gmail dot com>
- To: Florian Weimer <fweimer at redhat dot com>
- Cc: Andreas Schwab <schwab at suse dot de>, Arnd Bergmann <arnd at arndb dot de>, Zack Weinberg <zackw at panix dot com>, Alistair Francis <alistair dot francis at wdc dot com>, GNU C Library <libc-alpha at sourceware dot org>
- Date: Tue, 9 Jul 2019 15:57:32 -0700
- Subject: Re: [RFC v2 08/20] sysdeps/wait: Use waitid if avaliable
- References: <cover.1561421042.git.alistair.francis@wdc.com> <2df9d3878359585ac1cc46243fb6664f7a50b3b3.1561421042.git.alistair.francis@wdc.com> <CAKCAbMhyUiEZcfg-BNL_sqUAFmtEWCEgoyUwMGOdB_jLbvKJ6Q@mail.gmail.com> <87ftnx6i0m.fsf@oldenburg2.str.redhat.com> <CAK8P3a39tr-qbG4X8SnM=3M6VfV+LzOvE6pVBqByN0YcPkf42w@mail.gmail.com> <877e9950hj.fsf@oldenburg2.str.redhat.com> <CAK8P3a0P1f=922peKELqanZqSY3MAdNiUK70UvZaxy75pS-2Qw@mail.gmail.com> <CAK8P3a2hj24voTemN54gBKay+cKU3vd_dr=KVacWjrO5foH3Bg@mail.gmail.com> <87a7e522wb.fsf@oldenburg2.str.redhat.com> <CAK8P3a3b32CNaXfR1w8cJuGS1H7qPTKLZc0BDxf-oW20i7aXvw@mail.gmail.com> <87r27hzrjd.fsf@oldenburg2.str.redhat.com> <CAK8P3a2HC_Ki0tf9B_A3Tm5w9zqrVLO8JG8u_ohc8aoSEY5okw@mail.gmail.com> <87ef3hzqjw.fsf@oldenburg2.str.redhat.com> <CAK8P3a2QW7WNuK0_zu44_fp3qWh7iL2V6Mae+zx+iLjUP7CitQ@mail.gmail.com> <8736jwjqkq.fsf@oldenburg2.str.redhat.com> <mvm36jwux93.fsf@suse.de> <878st8u3qp.fsf@oldenburg2.str.redhat.com> <mvmlfx8emc2.fsf@suse.de> <87bly4snx5.fsf@oldenburg2.str.redhat.com>
On Mon, Jul 8, 2019 at 5:37 AM Florian Weimer <fweimer@redhat.com> wrote:
>
> * Andreas Schwab:
>
> > On Jul 08 2019, Florian Weimer <fweimer@redhat.com> wrote:
> >
> >> * Andreas Schwab:
> >>
> >>>> But this would still break if people actually go ahead with the removal
> >>>> of the 32-bit system calls (something I think is quite impossible to do,
> >>>> but some people seem to disagree).
> >>>
> >>> I'd expect that the current futex syscall will continue to work for all
> >>> its subfunctions without absolute timestamp.
> >>
> >> I thought that RV32 just wouldn't have a futex system call at all?
> >
> > I'm talking about legacy 32-bit architectures.
>
> Ah. Yes, I one would hope that.
>
> But there has been talk of a kernel option to remove it even there, and
> a suggestion that glibc would try the 64-bit time_t system call first,
> to see if it is available, and prefer that.
>
> I think this would be quite … wrong.
So that means that the #define solution (see below) is probably the
way to go then?
#if __riscv_xlen == 32
# ifndef __NR_futex
# define __NR_futex __NR_futex_time64
# endif
#endif
Alistair
>
> Thanks,
> Florian