Re: [PATCH v5 07/13] block: Add PCI P2P flag for request queue and check support for requests

Jens Axboe
2018-09-05T19:54:35Z

On 9/5/18 1:56 PM, Christoph Hellwig wrote:
> On Wed, Sep 05, 2018 at 01:45:04PM -0600, Jens Axboe wrote:
>> The point is that the caller doesn't necessarily know where the bio
>> will end up, hence the caller can't fully check if the whole stack
>> supports P2P.
>
> The caller must necessarily know where the bio will end up, as for P2P
> support we need to query if the bio target is P2P capable vs the
> source of the P2P memory.

Then what's the point of having the check at all?

--
Jens Axboe