Re: [PATCH]: Re: qla1280.c broken on SGI visws, PCI coherency problem

[Michael Reed <mdr@sgi.com>]

James Bottomley wrote:
> On Tue, 2005-12-13 at 07:22 -0600, Michael Reed wrote:
>> I believe the biggest issue with VISWS is that it appears to need
>> mmiowb() and we likely don't know how to implement it.  Hence, for
>> that platform, it would make sense to replace the mmiowb() with a
>> posting read.
> 
> Well, there's an easy way to tell ... the reason for the mmiowb in the
> qla1280 driver is supposed to be an SMP race, according to the
> description, so if it fails on UP as well there's something else going
> on here ...
> 
> I'm still suspicious because the mmiowb() in this driver replaced a
> posted write flush instruction, which altered the behaviour of the
> driver.  The qla1280 is just rare enough that it might have taken this
> long to notice ...

Yup.  But.... keep in mind that the failing platform is the SGI
VISWS, the child of a PC and an O2.  I'd be much more suspicious
if it failed on a generic PC.  (It also works fine on SGI Altix,
a platform which has implemented mmiowb().)

Perhaps Mr. Joosten can confirm his failing case with the UP kernel?

Mike

> 
> James
> 
>