Re: [Xen-devel] [RFC PATCH 2/3] arch, arm32: add the XEN_DOMCTL_memory_mapping hypercall

[Arianna Avanzini <avanzini.arianna@xxxxxxxxx>]

On 03/06/2014 04:41 AM, Julien Grall wrote:
> 
> 
> On 05/03/14 21:59, Arianna Avanzini wrote:
>> Hello,
> 
> Hello Arianna,
> 
>>> The comment "1:1 iomem mapping (gfn == mfn)" seems wrong here. The
>>> implementation you wrote allow gfn != mfn.
>>>
>>
>> Right, thank you.
>> Sorry if I bother you with one more question about this hunk; aside from the
>> error pointed out by Eric with the usage of pfn instead of paddr_t, is it OK 
>> to
>> map the address range all at once with map_mmio_regions() as proposed? I 
>> noticed
>> that the x86-related code seems to map the range one mfn at a time with
>> set_mmio_p2m_entry(), and I wonder if this different approach has any 
>> benefit I
>> didn't think about.
> 
> map_mmio_regions will take p2m lock and do MMU management (e.g TLB flush...).
> For the latter the code  has been written to only do TLB flush, if needed, 
> once
> per call. More the range is large, better it is.
> 
> So, it's better to call the function only once for the whole range.
> 

OK, thank you for the clear explanation.


> Regards,
> 


-- 
/*
 * Arianna Avanzini
 * avanzini.arianna@xxxxxxxxx
 * 73628@xxxxxxxxxxxxxxxxxxx
 */

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