[Xorg] The big multiconsole nasty
eich at pdx.freedesktop.org
Mon Jul 12 05:30:41 PDT 2004
Jesse Barnes writes:
> On Tuesday, July 6, 2004 9:36 am, Jon Smirl wrote:
> > --- John Dennis <jdennis at redhat.com> wrote:
> > > bus topology and that VGA routing is correct. Unlike the current
> > You can't make the assumptions about VGA routing. When secondary video
> > cards are reset by running their ROM, at the very least they enable
> > their VGA support. Sometimes they remap the bridges too.
> > We need kernel support for:
> > 1) disabling all VGA devices
> > 2) setting one VGA device active and get the bus routed to it
> This is possible, but also points out a deficiency in the current X server's
> idea of I/O ports. I spoke with John Dennis about this a few weeks ago, but
> it seems to me that we should either:
> o make the in/out routines take full pointers for the port address value
This is already done. All addresses in the code are already constructed
by using base+offset.
> - or -
> o pass a PCI tag to them so that the platform code can figure out where to
> route the I/O
I also had a similar idea years ago. However I dropped it again:
How about the latencies introduced when each IO operation has to
verify that it is routed correctly?
> As it stands, the X server's platform code has to assume one, global, I/O port
> base address...
Not true any more. Take a look at the AXP and PPC code. Possibly also the
On these platforms PIO is 'redirected' to MMIO and each bus has its distinct
range in the MMIO address space.
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