Date: Mon, 21 Jan 2008 16:01:45 -0500 From: David Schultz <das@FreeBSD.ORG> To: Jung-uk Kim <jkim@FreeBSD.ORG> Cc: freebsd-current@FreeBSD.ORG, freebsd-arch@FreeBSD.ORG Subject: Re: [RFC] SysV SHM on 64-bit platforms Message-ID: <20080121210145.GA9107@VARK.MIT.EDU> In-Reply-To: <200801211152.07680.jkim@FreeBSD.org> References: <200801181217.52788.jkim@FreeBSD.org> <20080119121316.GA21917@VARK.MIT.EDU> <200801211152.07680.jkim@FreeBSD.org>
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On Mon, Jan 21, 2008, Jung-uk Kim wrote: > On Saturday 19 January 2008 07:13 am, David Schultz wrote: > > For 8-CURRENT, I'd say go ahead and fix it and add the syscall > > compat goop. Then I guess backport it to 7-STABLE after a while if > > nothing important breaks and nobody has any objections to that > > plan. > > Well, since the policy is 'no seat belt for -CURRENT', I think that is > aceptable, too. Right, but you need the compat shims to avoid breaking the ABI when 8.0 is released anyway. > > It would also be cool if struct ipcperm got fixed at the same time > > so we only have to do this once. I think that only entails adding > > compat crud to semctl and maybe one or two other syscalls. Those > > changes aren't urgent enough to make it worthwhile to backport to > > 7.X IMO, though. > > So, you are in between option 1 and 4, i.e., bigger fix goes to HEAD > and partial MFC to RELENG_7, right? I'd say try to fix everything once and for all in HEAD, including struct ipcperm, but only MFC the shmid_ds changes to minimize the chance that anything breaks between 7.X releases. Others may have different opinions... > Actually, the arch check is > done like this: > > if (sizeof(size_t) != sizeof(int) && td->td_proc->p_osrel <= WHATEVER) > > I am hoping the compiler is smart enough to optimize away > 'sizeof(size_t) != sizeof(int)'. Yes, gcc does basic dead code elimination like this at all optimization levels, including -O0. Of course the code within the if block still has to be syntactically valid on all architectures; if it isn't, then you need ifdefs. > > - The 8.X version needs to take the p_osrel for the equivalent > > change in 7.X into account. > > I thought it did, didn't it? Oops, maybe you did and I was looking at one of the other versions of the patch.
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