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Re: glibc 2.21 - Machine maintainers, please test your machines.
- From: Torvald Riegel <triegel at redhat dot com>
- To: "H.J. Lu" <hjl dot tools at gmail dot com>
- Cc: Andreas Schwab <schwab at suse dot de>, Chris Metcalf <cmetcalf at ezchip dot com>, "Carlos O'Donell" <carlos at redhat dot com>, GNU C Library <libc-alpha at sourceware dot org>, David Miller <davem at davemloft dot net>, Richard Henderson <rth at redhat dot com>, Mike Frysinger <vapier at gentoo dot org>, "Joseph S. Myers" <joseph at codesourcery dot com>, Kaz Kojima <kkojima at rr dot iij4u dot or dot jp>, Thomas Schwinge <thomas at codesourcery dot com>, Marcus Shawcroft <marcus dot shawcroft at linaro dot org>, Chung-Lin Tang <chunglin_tang at mentor dot com>, Adhemerval Zanella <azanella at linux dot vnet dot ibm dot com>, Andreas Krebbel <krebbel at linux dot vnet dot ibm dot com>
- Date: Mon, 26 Jan 2015 13:50:15 +0100
- Subject: Re: glibc 2.21 - Machine maintainers, please test your machines.
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On Mon, 2015-01-26 at 04:44 -0800, H.J. Lu wrote:
> On Mon, Jan 26, 2015 at 1:24 AM, Andreas Schwab <schwab@suse.de> wrote:
> > "H.J. Lu" <hjl.tools@gmail.com> writes:
> >
> >> It doesn't change the size, only increases alignment from 4 bytes to 8 bytes.
> >
> > Alignment is part of the ABI.
> >
>
> For x32, we can increase alignment from 4 bytes to 8 bytes without breaking
> existing binaries.
But you'd still have to do the alignment check at runtime, because you
can't expect the application to have used the new headers with proper
alignment. Or are you saying that the alignment is just a performance
thing in the particular case of x32, because the atomics work either
way? If so, then using __alignof__(sem_t) in Chris' patch would be good
because then to_new_sem would resolve to a noop in x32 with your
alignment change applied.
- References:
- glibc 2.21 - Machine maintainers, please test your machines.
- Re: glibc 2.21 - Machine maintainers, please test your machines.
- Re: glibc 2.21 - Machine maintainers, please test your machines.
- Re: glibc 2.21 - Machine maintainers, please test your machines.
- Re: glibc 2.21 - Machine maintainers, please test your machines.
- Re: glibc 2.21 - Machine maintainers, please test your machines.
- Re: glibc 2.21 - Machine maintainers, please test your machines.
- Re: glibc 2.21 - Machine maintainers, please test your machines.
- Re: glibc 2.21 - Machine maintainers, please test your machines.
- Re: glibc 2.21 - Machine maintainers, please test your machines.
- Re: glibc 2.21 - Machine maintainers, please test your machines.