Re: [Xen-devel] Question about the dynamic sizing of the PCI hole

[Keir Fraser <keir.fraser@xxxxxxxxxxxxx>]

That field is updated dynamically. Can't you fluently read ASL? ;-)

 -- Keir

On 25/05/2009 10:24, "Tom Rotenberg" <tom.rotenberg@xxxxxxxxx> wrote:

> And, won't we have any problem if we dynamically size the PCI hole, and not
> update it in the DSDT we give for the HVM (in the DSDT it's always
> 0xf0000...)?
> 
> 2009/5/25 Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
>> On 25/05/2009 10:01, "Tom Rotenberg" <tom.rotenberg@xxxxxxxxx> wrote:
>> 
>>> I am reviewing the code of the hvmloader from Xen 3.4, and i saw that in
>>> changeset 19021, there was a patch which added the ability to dynamically
>>> size
>>> the PCI hole. I have seen that this patch calculates the total memory size,
>>> but i failed to understand the following lines:
>>> 
>>> while ( (mmio_total > (pci_mem_end - pci_mem_start)) &&
>>>             ((pci_mem_start << 1) != 0) )
>>>         pci_mem_start <<= 1;
>>> 
>>> It looks as if the pci mem start will be increased if there isn't enough
>>> space
>>> for the PCI devices, although, as far as i understand, it should be
>>> decreased
>>> (so the PCI hole will be enlarged). So, shouldn't it be: "pci_mem_start >> =
>>> 1" ?
>> 
>> Leading bits of this 32-bit value are 1s. Hence left shift is what we want.
>> 
>>  -- Keir
>> 
>> 
> 



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