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

To:	xen-devel@xxxxxxxxxxxxxxxxxxx
Subject:	[Xen-devel] Question about the dynamic sizing of the PCI hole
From:	Tom Rotenberg <tom.rotenberg@xxxxxxxxx>
Date:	Mon, 25 May 2009 12:01:15 +0300
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Hi,

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" ?

Thanks,
       Tom

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