lkml.org 
[lkml]   [2019]   [Sep]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [RFC PATCH] drm/virtio: Export resource handles via DMA-buf API
  Hi,

> To seamlessly enable buffer sharing with drivers using such frameworks,
> make the virtio-gpu driver expose the resource handle as the DMA address
> of the buffer returned from the DMA-buf mapping operation. Arguably, the
> resource handle is a kind of DMA address already, as it is the buffer
> identifier that the device needs to access the backing memory, which is
> exactly the same role a DMA address provides for native devices.

No. A scatter list has guest dma addresses, period. Stuffing something
else into a scatterlist is asking for trouble, things will go seriously
wrong when someone tries to use such a fake scatterlist as real scatterlist.

Also note that "the DMA address of the buffer" is bonkers in virtio-gpu
context. virtio-gpu resources are not required to be physically
contigous in memory, so typically you actually need a scatter list to
describe them.

cheers,
Gerd

\
 
 \ /
  Last update: 2019-09-12 14:41    [W:0.212 / U:0.876 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site