radeon, apertures & memory mapping

[Jon Smirl]

What about using the overlapped mode and dividing memory into four regions

FB0
PCI visible free mem
FB1
APER_SIZE
non-visible free mem

This way setting the mode on FB0 doesn't always bump into FB1.

The DRM could do this:
FB0
back0
depth0
aux0, etc
PCI visible free mem - textures priority 2
aux1, etc
depth1
back1
FB1
APER_SIZE
non-visible free mem - textures priority 1


On Sun, 13 Mar 2005 12:35:43 +1100, Benjamin Herrenschmidt
<benh at kernel.crashing.org> wrote:
> I could maybe use a single ioremap though, that is use a single
> aperture, and then switch the swapper on accesses. Though I should also
> be careful not to end up conflicting with a userland process relying on
> having the 2 separate aperture swappers stable for the mode on the 2
> separate framebuffer mappings... Like X would use fb0 while console
> would use fb1 with a different swapper setting. That would blow up for
> sure unless fbcon arbitrates accesses with X, which I don't see
> happening right away. I suppose we'll have to consider both heads linked
> as far as console ownership is concerned, at least for now, until the
> kernel console subsystem is overhauled significantly.

In the long term I was hoping to design thing such that the two heads
can be used by two independent users, each could be running X or
fbdev.

A user space console implementation also makes a lot of sense in the
multiuser case. User space console can be a DRI application instead of
fbdev reducing the need to map.

-- 
Jon Smirl
jonsmirl at gmail.com