On 11/10/2014 12:56 AM, Chris Wilson wrote:
On Mon, Nov 10, 2014 at 04:31:59PM +0800, Zhang Fan wrote:
Hi all,
I'm developing a video matrix system for Linux. Typically multiple
vendors' video card and/or multiple cards of same vendor/model might
be used in one system.
I can list the display by using 'xrandr' program and read the
display card information from /sys/class/drm/ directory. But I can't
figure out how to relate these two kinds information. i.e, which
card/port does a display belongs to?
'xrandr --verbose' command lists the 'Identifier' of each display
but it seems volatile and might change after reboot and has nothing
to do with the information in /sys/class/drm.
If your devices support DRI2/DRI3, you can send a DRI request to query
the device node for a screen. Might be a nice extension to xrandr
--verbose, or perhaps a new dri[23]info.
Seems like that would make a pretty good standard property for RandR
Provider objects.
In general, there's no 1-1 mapping from an X screen to a GPU. E.g.,
with the NVIDIA driver with SLI enabled, multiple GPUs are used to
render one screen. With various forms of PRIME, multiple GPUs can be
used to handle various aspects of rendering or scanout on a single X screen.
-Chris
--
Aaron
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