On Thu, Jul 23, 2020 at 02:10:52PM -0600, Logan Gunthorpe wrote: > On 2020-07-23 1:57 p.m., Bjorn Helgaas wrote: > > On Thu, Jul 23, 2020 at 02:01:17PM -0400, Alex Deucher wrote: > >> On Thu, Jul 23, 2020 at 1:43 PM Logan Gunthorpe <logang@xxxxxxxxxxxx> wrote: > >>> > >>> The AMD Zen 2 root complex (Starship/Matisse) was tested for P2PDMA > >>> transactions between root ports and found to work. Therefore add it > >>> to the list. > >>> > >>> Signed-off-by: Logan Gunthorpe <logang@xxxxxxxxxxxx> > >>> Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx> > >>> Cc: Christian König <christian.koenig@xxxxxxx> > >>> Cc: Huang Rui <ray.huang@xxxxxxx> > >>> Cc: Alex Deucher <alexdeucher@xxxxxxxxx> > >> > >> Starting with Zen, all AMD platforms support P2P for reads and writes. > > > > What's the plan for getting out of the cycle of "update this list for > > every new chip"? Any new _DSMs planned, for instance? > > Well there was an effort to add capabilities in the PCI spec to describe > this but, as far as I know, they never got anywhere, and hardware still > doesn't self describe with this. Any idea what happened? Is there hope for the future? I'm really not happy about signing up for open-ended device-specific patches like this. It's certainly not in the plug and play spirit that has made PCI successful. I know, preaching to the choir here. Bjorn
