Re: [Qemu-trivial] [PATCH] vfio/pci: replace 1 with PCI_CAP_LIST_NEXT to make code self-explain

[Paolo Bonzini]

On 16/03/2016 12:27, Michael Tokarev wrote:
>> >      for (tmp = pdev->config[PCI_CAPABILITY_LIST]; tmp;
>> > -         tmp = pdev->config[tmp + 1]) {
>> > +         tmp = pdev->config[tmp + PCI_CAP_LIST_NEXT]) {
>> > -    next = pdev->config[pos + 1];
>> > +    next = pdev->config[pos + PCI_CAP_LIST_NEXT];
> Hmm. I'm not sure the new version is better, to me "+1" reads
> easier than the new symbolic constant variant.
> 
> If it were something like pdev->config[PCI_CAP_LIST_NEXT], that'd be
> nice, but not "pos + PCI_CAP_LIST_NEXT".
> 
> But again, I'm not pci config space expert and don't understand
> the basics :)

Each capability is a node of a linked list, and the position of the next
capability is at offset 1 inside the capability (here it is at offset 1
from the tmp or pos base).  I think the patch is an improvement.

Paolo