Date: Fri, 18 Mar 2011 06:57:29 +1100 From: Peter Jeremy <peterjeremy@acm.org> To: Jung-uk Kim <jkim@FreeBSD.org> Cc: src-committers@FreeBSD.org, Roman Divacky <rdivacky@FreeBSD.org>, Bruce Evans <brde@optusnet.com.au>, svn-src-head@FreeBSD.org, svn-src-all@FreeBSD.org, Maxim Dounin <mdounin@mdounin.ru> Subject: Re: svn commit: r219679 - head/sys/i386/include Message-ID: <20110317195729.GA65858@server.vk2pj.dyndns.org> In-Reply-To: <201103161634.08104.jkim@FreeBSD.org> References: <201103152145.p2FLjAlt060256@svn.freebsd.org> <201103161233.16347.jkim@FreeBSD.org> <20110316174553.GA6367@freebsd.org> <201103161634.08104.jkim@FreeBSD.org>
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--T4sUOijqQbZv57TR Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On 2011-Mar-16 16:34:04 -0400, Jung-uk Kim <jkim@FreeBSD.org> wrote: >On Wednesday 16 March 2011 01:45 pm, Roman Divacky wrote: >> if we drop i486 I think it makes sense to require something that >> has at least SSE2, thus we can have the same expectations as on >> amd64. I think it's stil a bit early for that - especially the SSE2 requirement. >This is a proof-of-concept patch for sys/x86/isa/clock.c: > >http://people.freebsd.org/~jkim/clock.diff > >You see the complexity, just because I wanted to load 64-bit value=20 >atomically... :-( An alternative approach is to have _fetch_frequency() be uint64_t (*_fetch_frequency)(uint64_t *); if i386 and I486 are defined (otherwise it's just the #define (*(p))) then initialise it to either atomic_fetch_quad_i386 or atomic_fetch_quad_i586 as part of the CPU detection process. This is the way bcopy() is/was handled on Pentium. Another approach would be to always have cmpxchg8b instructions (followed by a suitably large NOP) always inlined in the code and if it traps, patch the code to call a function that emulates it. --=20 Peter Jeremy --T4sUOijqQbZv57TR Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.17 (FreeBSD) iEYEARECAAYFAk2CZ6kACgkQ/opHv/APuIf4HgCglRSBF80GZRoaO3asSrakTbct VKoAoI9R8PNjJjwCUnvVIyuvNqobcboa =7WMx -----END PGP SIGNATURE----- --T4sUOijqQbZv57TR--
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