Re: [PATCH] vga: implements VGA arbitration on Linux

[Jesse Barnes]

On Tue, 11 Aug 2009 16:17:46 -0700
Jesse Barnes <jesse.barnes@xxxxxxxxx> wrote:

> On Tue, 11 Aug 2009 15:52:06 +1000
> Dave Airlie <airlied@xxxxxxxxx> wrote:
> 
> > From: Tiago Vignatti <tiago.vignatti@xxxxxxxxx>
> > 
> > Background:
> > Graphic devices are accessed through ranges in I/O or memory space.
> > While most modern devices allow relocation of such ranges, some
> > "Legacy" VGA devices implemented on PCI will typically have the same
> > "hard-decoded" addresses as they did on ISA. For more details see
> > "PCI Bus Binding to IEEE Std 1275-1994 Standard for Boot
> > (Initialization Configuration) Firmware Revision 2.1" Section 7,
> > Legacy Devices.
> > 
> > The Resource Access Control (RAC) module inside the X server
> > currently does the task of arbitration when more than one legacy
> > device co-exists on the same machine. But the problem happens when
> > these devices are trying to be accessed by different userspace
> > clients (e.g. two server in parallel). Their address assignments
> > conflict. Therefore an arbitration scheme _outside_ of the X server
> > is needed to control the sharing of these resources. This document
> > introduces the operation of the VGA arbiter implemented for Linux
> > kernel.
> > 
> > Signed-off-by: Tiago Vignatti <tiago.vignatti@xxxxxxxxx>
> > Signed-off-by: Dave Airlie <airlied@xxxxxxxxxx>
> 
> Ok, applied this to my linux-next branch, but I'd like to get Ben's
> s-o-b before pushing it to Linus.

Oh yeah, and we should get the documentation merged too.  I can handle
that or you can send it to Randy.  Tiago?

-- 
Jesse Barnes, Intel Open Source Technology Center
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