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

["Jan Beulich" <jbeulich@xxxxxxxxxx>]

I/O can at least theoretically exist anywhere in that space, not just in
the VGA range. Also, mapping ROM WB seems suspicious at least - you're
relying on MTRR settings then without really needing to. 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).

Jan

>>> Keir Fraser <Keir.Fraser@xxxxxxxxxxxx> 29.01.08 11:20 >>>
Isn't the memory map below 1MB well known, and no I/O exists down there
except for VGA? Below that is conventional RAM; above that is ROM space.

 -- Keir

On 29/1/08 10:05, "Jan Beulich" <jbeulich@xxxxxxxxxx> wrote:

> Don't you think that it would also be reasonable to map all of the RAM
> holes below 1M uncacheable, not just the VGA space? Since early boot
> code can't know this, I added a map_pages_to_xen(...,
> PAGE_HYPERVISOR_NOCACHE) for the below-1Mb case of the code
> that you just fixed.
> 
> Jan
> 
>>>> Keir Fraser <Keir.Fraser@xxxxxxxxxxxx> 29.01.08 10:37 >>>
> Fixed by c/s 16926.
> 
>  -- Keir
> 
> On 29/1/08 05:58, "Li, Haicheng" <haicheng.li@xxxxxxxxx> wrote:
> 
>> Xen hangs on booting with following log printed:
>> 
>> (XEN) Initializing CPU#0
>> (XEN) Detected 2992.574 MHz processor.
>> (XEN) (XEN) (XEN) (XEN) (XEN)
>> 
>> This issue was introduced by c/s 16889.
>> 
>> Here is the bugzilla entry:
>> http://bugzilla.xensource.com/bugzilla/show_bug.cgi?id=1157 
>> 
>> -- haicheng
>> 
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> 
> 
> 
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