[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Xen-devel] Xen hypervisor hangs on booting against c/s 16925



>>> Keir Fraser <Keir.Fraser@xxxxxxxxxxxx> 29.01.08 11:45 >>>
>On 29/1/08 10:34, "Jan Beulich" <jbeulich@xxxxxxxxxx> wrote:
>
>> Otoh, with
>> PAGE_HYPERVISOR_NOCACHE encoding UC- rather than UC, mapping
>> WP MTRR regions this way would yield (model specific) WC, which again
>> seems suspicious, so maybe the VGA hole should simply be kept (from
>> boot, at UC-), but everything else should be forced to UC (or MTRRs
>> should be inquired so that at least WP regions can be kept WP).
>
>If we don't write to a MTRR WP region, then actually mapping as WC does not
>matter. We never write to the range 0xc0000-0xfffff. Anything we write to
>below 0xa0000 had better be RAM, or we've got bigger problems than the WP
>attribute!

Unfortunately it does matter - WC does not permit read caching, but
does permit speculative reads. That's both not what we want.

Jan


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel


 


Rackspace

Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.