Re: [Xen-devel] xen/arm: Alternative start of day cache coherency

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Wed, 2014-01-22 at 19:06 +0000, Julien Grall wrote:
> On 01/22/2014 04:35 PM, Ian Campbell wrote:
> > Julien,
> 
> Hi Ian,
> 
> > I wonder if the following is any better than the current stuff in
> > staging for the issue you are seeing with BSD at start of day? Can you
> > try it please.
> 
> Thanks for the patch! It allows me to boot FreeBSD correctly (ie with
> Write-Through for the first page table) on Midway.

Perfect. I'm inclined to put clean this up and put it forward for 4.4
then.

> > It has survived >1000 bootloops on Midway and >50 on Mustang, both are
> > still going.
> > 
> > It basically does a cache clean on all RAM mapped in the p2m. Anything
> > in the cache is either the result of an earlier scrub of the page or
> > something toolstack just wrote, so there is no need to be concerned
> > about clean vs. invalidate -- clean is always correct.
> 
> I don't remember what was the conclusion... is it necessary to flush all
> the RAM? Flushing the Kernel/initrd/DTB space should be enough.

See my reply to Stefano -- we need to be concerned about scrubbed page
data in the cache which is masking actual data from the previous owner.

Ian.



_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel