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

  • To: Jan Beulich <jbeulich@xxxxxxxxxx>
  • From: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
  • Date: Tue, 29 Jan 2008 10:55:47 +0000
  • Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
  • Delivery-date: Tue, 29 Jan 2008 02:56:25 -0800
  • List-id: Xen developer discussion <xen-devel.lists.xensource.com>
  • Thread-index: AchiZYCrvxLEg85YEdyyYwAX8io7RQ==
  • Thread-topic: [Xen-devel] Xen hypervisor hangs on booting against c/s 16925

Does Linux have a permanent mapping, indeed a superpage mapping, of the
bottom megabyte? I think it does. The fact that this persists in the Linux
kernel, which is thoroughly tested on many many platforms, I think indicates
we are over-worrying about mappings of the bottom megabyte.

 -- Keir

On 29/1/08 10:54, "Jan Beulich" <jbeulich@xxxxxxxxxx> wrote:

> .. which is bad, and should probably be changed, too. Jan
>>>> Keir Fraser <Keir.Fraser@xxxxxxxxxxxx> 29.01.08 11:40 >>>
> Also, bear in mind that dom0 permanently has a WB mapping of the whole
> bottom megabyte.
>  -- Keir
> On 29/1/08 10:36, "Keir Fraser" <Keir.Fraser@xxxxxxxxxxxx> wrote:
>> 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

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