Re: [PATCHSET] block: fix PIO cache coherency bug

From: Guennadi Liakhovetski
Date: Tue May 30 2006 - 17:06:35 EST


On Tue, 30 May 2006, Tejun Heo wrote:

> Nicolas Pitre wrote:
> > Has any discussion about this problem lead to some consensus?
>
> Argghhh.. I completely forgot about this.
>
> > > What do you think of the kmap_atomic_pio() (notoriously bad at names,
> > > but it should get the point across) and kunmap_atomic_pio(), the latter
> > > accepting a read/write flag to note if we wrote to a vm page?
> > >
> > > This is basically Tejuns original patch set, just moving it out of the
> > > block layer so it's a generel exported property of the kmap api.
> >
> > What was the problem with Tejun's patchset already to which RMK (and many
> > others) agreed?
> >
> > I do have hardware that exhibits the problem and therefore I wish the
> > discussion could be resumed.

Partly to add myself to the cc-list, partly to add some oil in the fire -
there have been a few discussions on arm-kernel recently, one of them

http://marc.theaimsgroup.com/?t=114136178100001&r=1&w=2

where at least you can get some more test results / failure pictures.
However, many have also stated that the patch set from Tejun,
unfortunately, doesn't fix 100% of IDE PIO cache coherency problems on
ARM.

Thanks for bringing this back up
Guennadi
---
Guennadi Liakhovetski
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