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From: Warner Losh <imp@bsdimp.com>
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Cc: mj@feral.com, freebsd-arch@FreeBSD.org
Subject: Re: newbus IO ordering semantics - moving forward
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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