Re: [PATCH v2 1/9] PCI/P2PDMA: Add CONFIG_PCI_P2PDMA_CORE

[Pranjal Shrivastava <praan@google.com>]

On Fri, May 29, 2026 at 08:05:53PM -0300, Jason Gunthorpe wrote:
> On Wed, May 27, 2026 at 03:09:46PM -0600, Alex Williamson wrote:
> > This deserves a /* CONFIG_PCI_P2PDMA */ reference like the previous
> > long span, though potentially a better solution would be to split the
> > core code out to a separate file with shared header.  I asked opus to
> > see what this would look like and it generated the patch below
> > (unverified, compile tested only).  Bigger diff, harder to follow
> > blame, but the shape of the core is much more apparent.  You're welcome
> > to take or leave it.
> 
> I think it is a good idea, it will make it easier to add more stuff to
> these different aspects.
> 
> Really they are now two different things with one layered on top of
> the other.
> 

A little late to this party. I agree with this split per status quo.
Although, one observation from me, I've posted a concurrent RFC [1] that
implements ZONE_DEVICE P2P registration for VFIO. That work relies on
pci_p2pdma_add_resource(), which requires ZONE_DEVICE and the full
CONFIG_PCI_P2PDMA stack rather than just the CORE part.

I guess I can be careful to guard the ZONE_DEVICE P2P registration 
feature in VFIO with the full PCI_P2PDMA config. Apart from that, this
split provides a clean foundation for both series to coexist.

Thanks,
Praan

[1] https://lore.kernel.org/all/20260610151853.3608948-1-praan@google.com/