newbus IO ordering semantics - moving forward

[Warner Losh]

On Oct 27, 2011, at 3:05 PM, Adrian Chadd wrote:

> On 28 October 2011 04:39, Matthew Jacob <mj at feral.com> wrote:
> 
>> 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.
>> 
>> I also am not sure I agree with your characterization of linux semantics.
> 
> Hi,
> 
> The point is, all (most?) of the bus glue does flushes if needed. Ie,
> if I understand what's going on:
> 
> * 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