Re: [Xen-devel] [PATCH] domain builder: Fix sp_extents allocation

[Keir Fraser <keir.fraser@xxxxxxxxxxxxx>]

On 31/7/08 12:29, "Samuel Thibault" <samuel.thibault@xxxxxxxxxxxxx> wrote:

> Keir Fraser, le Thu 31 Jul 2008 12:19:18 +0100, a écrit :
>> Doesn't this turn the array allocation into a dynamic allocation? I feel a
>> bit dubious about that.
> 
>>>          {
>>>              long done;
>>> -            xen_pfn_t sp_extents[2048 >> SUPERPAGE_PFN_SHIFT];
>>> +            xen_pfn_t sp_extents[count >> SUPERPAGE_PFN_SHIFT];
>>>              struct xen_memory_reservation sp_req = {
> 
> Err, I'd think that it just turns a
> 
> sub (2048>>SUPERPAGE_PFN_SHIFT) * sizeof(xen_pfn_t), %esp
> 
> into a
> 
> mov count, %eax
> shr SUPERPAGE_PFN_SHIFT - log2(sizeof(xen_pfn_t)), %eax
> sub %eax, %esp

Yes, good point!

 -- Keir



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