Adjusting basic video driver testcase for UEFI systems

Adam Jackson ajax at
Thu Jul 11 18:02:55 UTC 2013

On Thu, 2013-07-11 at 08:25 -0400, Jan Sedlak wrote:

> From what I read [2, 3], it seems that UEFI systems don't support VESA graphic
> mode. I must admit that I don't fully understand what's the state of UEFI
> graphic protocols (there is GOP and UGA protocols, but I don't know whether
> Linux supports them), so if there is anyone who knows how graphic fallback
> should be handled on UEFI systems, please share your knowledge with us.

UGA is old and broken, and I don't think we have any support for it.
GOP is what anything you can buy these days has, and it's supported with
the efifb kernel driver.  If we ever were to support UGA it'd be in
efifb too, so it doesn't really matter.

In fact on UEFI systems efifb _always_ loads, and if accelerated
graphics is enabled there's a handoff from efifb to the appropriate DRM
driver.  But if you say 'nomodeset' on kcmdline you'll stick with efifb
at runtime, so in that sense testing this is the same as with BIOS

The visible difference at X time is that you'll be using the fbdev
driver instead of the vesa driver, and that RANDR won't work.  That's a
UEFI limitation: all the code to do mode setting in GOP is only
available in the pre-OS phase, once the kernel's loaded you're stuck
with whatever the firmware (well, grub) gave you.

- ajax

More information about the test mailing list