Date: Thu, 27 Oct 2011 15:16:30 -0600 From: Warner Losh <imp@bsdimp.com> To: Adrian Chadd <adrian@FreeBSD.org> Cc: mj@feral.com, freebsd-arch@FreeBSD.org Subject: Re: newbus IO ordering semantics - moving forward Message-ID: <02D4199D-851F-4AA4-8E56-F18B7EF0E79A@bsdimp.com> In-Reply-To: <CAJ-Vmomuze%2BfX_NRhB11dJbZX54c=Gqj6EpxjjnP17BtZxCaNQ@mail.gmail.com> References: <CAJ-VmonFJG3xLn2JvarOUN6o-e7MC%2BA%2B=W9_vocZqY6L3CmTmQ@mail.gmail.com> <4EA9C197.9080407@feral.com> <CAJ-Vmomuze%2BfX_NRhB11dJbZX54c=Gqj6EpxjjnP17BtZxCaNQ@mail.gmail.com>
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On Oct 27, 2011, at 3:05 PM, Adrian Chadd wrote: > On 28 October 2011 04:39, Matthew Jacob <mj@feral.com> wrote: >=20 >> No. Please don't change the current semantics which are well = understood if >> only fitfully adhered to. This would put us in the position of having = some >> drivers possibly work slower because they didn't do the "lazy" = request. >>=20 >> I also am not sure I agree with your characterization of linux = semantics. >=20 > Hi, >=20 > The point is, all (most?) of the bus glue does flushes if needed. Ie, > if I understand what's going on: >=20 > * amd64/intel, it's not needed; > * mips doesn't implement it yet; Sounds like a mips bug to me. > * ppc (and sparc?) implement a bus flush on each operation anyway. If ppc implements the flush like you say, how is it you found a bug in = ppc from missing flushes? Warner
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