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Date:   Fri, 7 Dec 2018 14:33:17 +0000 (GMT)
From:   "Maciej W. Rozycki" <macro@linux-mips.org>
To:     Florian Weimer <fweimer@redhat.com>
cc:     Joseph Myers <joseph@codesourcery.com>,
        Paul Burton <paul.burton@mips.com>,
        Firoz Khan <firoz.khan@linaro.org>,
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        Ralf Baechle <ralf@linux-mips.org>,
        James Hogan <jhogan@kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Philippe Ombredanne <pombredanne@nexb.com>,
        Thomas Gleixner <tglx@linutronix.de>,
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        Deepa Dinamani <deepa.kernel@gmail.com>,
        Marcin Juszkiewicz <marcin.juszkiewicz@linaro.org>,
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Subject: Re: [PATCH v3 0/6] mips: system call table generation support
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On Thu, 6 Dec 2018, Florian Weimer wrote:

> >  I seem to remember having to take extra care with how the three MIPS ABIs 
> > wire the syscalls to get it right in glibc, but I take it then this has 
> > been now addressed reliably enough for the glibc not to care how exactly
> > <asm/unistd.h> has been arranged.
> 
> This is a fairly recent change (commit
> 2dba5ce7b8115d6a2789bf279892263621088e74, "<bits/syscall.h>: Use an
> arch-independent system call list on Linux", first release with it is
> glibc 2.27).  This patch is quite backportable; we have put it into our
> 2.17-derived glibc, and the upstream work was originally driven by
> downstream ordering requirements of kernel header and glibc builds.
> Glad to see it's useful elsewhere.

 Thanks for the pointer, and the work you have done to make this more 
robust; it was that that I missed.

> The test retains the old <asm/unistd.h>-based macro extraction for
> testing purposes, but it needs that only for the actual target
> architecture and only the *names*, so it's easy to implement.  Before
> that, the generation would have to carefully take into account multiple
> sub-targets (i386/x86-64/x32 is one of the more complicated scenarios).
> Presumably, you saw problem with that part.

 Yeah, the MIPS o32/n64/n32 ABI set is a corresponding situation, except 
that somewhat longer-lived as we've had support for these three ABIs since 
2001, including the ability to concurrently run user executables built for 
any of these ABIs under a single 64-bit Linux kernel.

  Maciej