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From:   Arnd Bergmann <arnd@arndb.de>
Date:   Wed, 3 Jul 2019 21:47:36 +0200
Message-ID: <CAK8P3a1zJPiR06uxZ5QVoEyDU64v=oUu_p9X-mULLeXN-som8A@mail.gmail.com>
Subject: Re: [PATCH 2/2] riscv/include/uapi: Define a custom __SIGINFO struct
 for RV32
To:     Alistair Francis <alistair23@gmail.com>
Cc:     Alistair Francis <alistair.francis@wdc.com>,
        linux-riscv-bounces@lists.infradead.org,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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On Wed, Jul 3, 2019 at 8:45 PM Alistair Francis <alistair23@gmail.com> wrote:
>
> On Wed, Jul 3, 2019 at 1:41 AM Arnd Bergmann <arnd@arndb.de> wrote:
> >
> > On Wed, Jul 3, 2019 at 2:21 AM Alistair Francis
> > <alistair.francis@wdc.com> wrote:
> > >
> > > The glibc implementation of siginfo_t results in an allignment of 8 bytes
> > > for the union _sifields on RV32. The kernel has an allignment of 4 bytes
> > > for the _sifields union. This results in information being lost when
> > > glibc parses the siginfo_t struct.
> >
> > I think the problem is that you incorrectly defined clock_t to 64-bit,
> > while it is 32 bit in the kernel. You should fix the clock_t definition
> > instead, it would otherwise cause additional problems.
>
> That is the problem. I assume we want to change the kernel to use a
> 64-bit clock_t.

Certainly not!

Doing so would likely involve deprecating all system calls that
take a clock_t (anything passing a struct siginfo or struct tms) and
replacements based on clock64_t.

> What I don't understand though is how that impacted this struct, it
> doesn't use clock_t at all, everything in the struct is an int or
> void*.

si_utime/si_stime in siginfo are clock_t.

      Arnd