This is the mail archive of the
libc-alpha@sourceware.org
mailing list for the glibc project.
Re: [PATCH v2] handle sem_t with ILP32 and __HAVE_64B_ATOMICS
- From: Joseph Myers <joseph at codesourcery dot com>
- To: Carlos O'Donell <carlos at redhat dot com>
- Cc: Chris Metcalf <cmetcalf at ezchip dot com>, Andreas Schwab <schwab at suse dot de>, Torvald Riegel <triegel at redhat dot com>, GNU C Library <libc-alpha at sourceware dot org>, "H.J. Lu" <hjl dot tools at gmail dot com>, David Miller <davem at davemloft dot net>, Richard Henderson <rth at redhat dot com>, Mike Frysinger <vapier at gentoo dot org>, 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: Tue, 27 Jan 2015 23:31:02 +0000
- Subject: Re: [PATCH v2] handle sem_t with ILP32 and __HAVE_64B_ATOMICS
- Authentication-results: sourceware.org; auth=none
- References: <54C2BDD7 dot 7000304 at redhat dot com> <54C3B6D5 dot 3090308 at ezchip dot com> <1422119595 dot 29655 dot 42 dot camel at triegel dot csb> <54C5094A dot 8060300 at ezchip dot com> <54C51D94 dot 6030007 at ezchip dot com> <1422276280 dot 29655 dot 91 dot camel at triegel dot csb> <54C6A1DD dot 4020004 at ezchip dot com> <1422305739 dot 29655 dot 144 dot camel at triegel dot csb> <87a915b170 dot fsf at igel dot home> <54C6CF4B dot 1020600 at ezchip dot com> <54C71485 dot 8060705 at redhat dot com> <54C80167 dot 7050106 at ezchip dot com> <54C8037A dot 1030307 at redhat dot com>
On Tue, 27 Jan 2015, Carlos O'Donell wrote:
> > I am certainly willing to use 32-bit atomics here for now. The absolutely
> > minimal change is to change tilegx32 to set __HAVE_64B_ATOMICS to 0.
> > Obviously the AArch64 ILP32 mode (out of tree) will want to do the same.
> > And I don't know whether m68k or mips require a similar change or if
> > they can tolerate unaligned 64-bit atomic operations. So arguably if
> > we can decide that my proposed re-aligning change is best, then it also
> > automatically handles all the other platforms as well.
>
> I would like several more rounds of review of your realigning code.
>
> You have my permission to checkin the minimal change for tilegx32.
>
> Similarly other ILP32 with 64-bit atomic arches should do the same,
> and we can continue this conversation without the pressure of the
> time boxed release.
Is __HAVE_64B_ATOMICS used *only* for semaphores? Because if there are
other effects of changing it, doing so seems risky - it would be better to
have a define such as SEM_USE_64B_ATOMICS, and make that default to 0 for
ILP32 architectures.
--
Joseph S. Myers
joseph@codesourcery.com