[PATCH v4 0/2] block: Enable proper MMIO memory handling for P2P DMA

[Jens Axboe]

On 11/13/25 12:52 PM, Keith Busch wrote:
> On Thu, Nov 13, 2025 at 10:45:53AM -0700, Jens Axboe wrote:
>> I took a look, and what happens here is that iter.p2pdma.map is 0 as it
>> never got set to anything. That is the same as PCI_P2PDMA_MAP_UNKNOWN,
>> and hence we just end up in a BLK_STS_RESOURCE. First of all, returning
>> BLK_STS_RESOURCE for that seems... highly suspicious. That should surely
>> be a fatal error. And secondly, this just further backs up that there's
>> ZERO testing done on this patchset at all. WTF?
>>
>> FWIW, the below makes it boot just fine, as expected, as a default zero
>> filled iter then matches the UNKNOWN case.
> 
> I think this must mean you don't have CONFIG_PCI_P2PDMA enabled. The

Right, like most normal people :-)

> state is never set in that case, but I think it should have been.

If you want the patchset to boot, yes it should have been...

-- 
Jens Axboe