Messages in this thread | | | From | Jason Gunthorpe <> | Subject | Re: [RFC PATCH 3/5] mm/vma: add support for peer to peer to device vma | Date | Wed, 30 Jan 2019 17:39:07 +0000 |
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On Wed, Jan 30, 2019 at 06:26:53PM +0100, Christoph Hellwig wrote: > On Wed, Jan 30, 2019 at 10:55:43AM -0500, Jerome Glisse wrote: > > Even outside GPU driver, device driver like RDMA just want to share their > > doorbell to other device and they do not want to see those doorbell page > > use in direct I/O or anything similar AFAICT. > > At least Mellanox HCA support and inline data feature where you > can copy data directly into the BAR. For something like a usrspace > NVMe target it might be very useful to do direct I/O straight into > the BAR for that.
It doesn't really work like that.
The PCI-E TLP sequence to trigger this feature is very precise, and the data requires the right headers/etc. Mixing that with O_DIRECT seems very unlikely.
Jason
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