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

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

How about we just map the whole megabyte UC- at start of day? We rarely
touch anything down there and when we do it'll mostly be BIOS tables (hence
in ROM and hence not marked as RAM in e820 and hence your approach would
have them also marked UC-). That at least has the tangible benefit of
removing a few lines of (assembly) code. :-)

 -- Keir

On 29/1/08 10:34, "Jan Beulich" <jbeulich@xxxxxxxxxx> wrote:

> 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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>>> http://lists.xensource.com/xen-devel
>> 
>> 
>> 
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>> 
> 
> 
> 



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