[Xen-devel] Re: [patch 06/26] Xen-paravirt_ops: paravirt_ops: allocate a fixmap slot

[Jeremy Fitzhardinge <jeremy@xxxxxxxx>]

Ingo Molnar wrote:
> * Jeremy Fitzhardinge <jeremy@xxxxxxxx> wrote:
>
>   
>> Allocate a fixmap slot for use by a paravirt_ops implementation.  Xen 
>> uses this to map the hypervisor's shared info page, which doesn't have 
>> a pseudo-physical page number, and therefore can't be mapped 
>> ordinarily.
>>     
>
> why not vmalloc it on the guest side? fixmaps are bad for this purpose 
> for a general paravirt implementation, it limits the size of the shared 
> info page, etc.

Yes.  vmalloc would have the annoying side-effect of actually allocating
some pages which would be shadowed by the remapping, but I guess
get_vm_area would do the job.  I'll give it a go.

    J

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