Date: Wed, 18 May 2016 12:36:37 -0700 From: Adrian Chadd <adrian.chadd@gmail.com> To: Ian Lepore <ian@freebsd.org> Cc: Nathan Whitehorn <nwhitehorn@freebsd.org>, Justin Hibbits <chmeeedalf@gmail.com>, Scott Long <scottl@freebsd.org>, "src-committers@freebsd.org" <src-committers@freebsd.org>, "svn-src-all@freebsd.org" <svn-src-all@freebsd.org>, "svn-src-head@freebsd.org" <svn-src-head@freebsd.org> Subject: Re: svn commit: r300154 - head/sys/net Message-ID: <CAJ-Vmo=gni2TdQ%2Bkxx8B-1WVVKP6GHfd4Rpn0f2AOA93ti0Jmg@mail.gmail.com> In-Reply-To: <1463592737.1180.294.camel@freebsd.org> References: <201605181545.u4IFjCKD030751@repo.freebsd.org> <20160518105033.1eae7432@zhabar.knownspace> <759d085c-a485-c2ed-5d70-26eb4d27cdc2@freebsd.org> <1463592737.1180.294.camel@freebsd.org>
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On 18 May 2016 at 10:32, Ian Lepore <ian@freebsd.org> wrote: > On Wed, 2016-05-18 at 10:14 -0700, Nathan Whitehorn wrote: >> >> On 05/18/16 08:50, Justin Hibbits wrote: >> > On Wed, 18 May 2016 15:45:12 +0000 (UTC) >> > Scott Long <scottl@FreeBSD.org> wrote: >> > >> > > Author: scottl >> > > Date: Wed May 18 15:45:12 2016 >> > > New Revision: 300154 >> > > URL: https://svnweb.freebsd.org/changeset/base/300154 >> > > >> > > Log: >> > > Activate the NO_64BIT_ATOMICS code for mips and powerpc >> > > >> > > Modified: >> > > head/sys/net/mp_ring.c >> > > >> > > Modified: head/sys/net/mp_ring.c >> > > ================================================================= >> > > ============= >> > > --- head/sys/net/mp_ring.c Wed May 18 15:44:45 2016 >> > > (r300153) +++ head/sys/net/mp_ring.c Wed May 18 15:45:12 >> > > 2016 (r300154) @@ -37,15 +37,17 @@ __FBSDID("$FreeBSD$"); >> > > #include <sys/malloc.h> >> > > #include <machine/cpu.h> >> > > >> > > - >> > > - >> > > -#include <net/mp_ring.h> >> > > +#if defined(__powerpc__) || defined(__mips__) >> > > +#define NO_64BIT_ATOMICS >> > > +#endif >> > > >> > > #if defined(__i386__) >> > > #define atomic_cmpset_acq_64 atomic_cmpset_64 >> > > #define atomic_cmpset_rel_64 atomic_cmpset_64 >> > > #endif >> > > >> > > +#include <net/mp_ring.h> >> > > + >> > > union ring_state { >> > > struct { >> > > uint16_t pidx_head; >> > > >> > powerpc64 defines both __powerpc__ and __powerpc64__, so you're >> > killing >> > atomics on powerpc64 with this. >> > >> > - Justin >> > >> >> Don't all of our 64-bit platforms have 64-bit atomics? So you could >> just >> #if defined(__LP64__) || defined(__i386__) || >> defined(__whatever_the_thing_is_for_mips_n32__) >> -Nathan >> > > It may be more complicated than that, though. armv6 can do 64-bit > atomics even tho it's 32-bit. armv4, also 32-bit, can do 64-bit > atomics in the kernel but not in userland. > > Maybe machine/atomic.h needs a #define that says whether 64-bit ops are > available in the current compilation unit. (And likewise for other bit > sizes if we have arches that have other limitations.) Please, please do this. Don't do a list of platforms, do a list of features. Pretty please. -adrian
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