[Xorg] The big multiconsole nasty

[Jon Smirl]

--- Keith Packard <keithp at keithp.com> wrote:
> Around 16 o'clock on Jun 29, Alan Cox wrote:
> 
> > 1. Multiple video cards means making RAC work across *multiple* X
> > servers running at once on a system each with its own console
> 
> A significant amount of the RAC effort involves sharing the standard
> VGA 
> I/O port and video memory addresses; if we accept that supporting
> multiple ISA
> video cards isn't along the critical path, we can probably delay a
> large 
> portion of this work and focus only on getting cards POSTed at boot
> time.

I have code that could be added to DRM that:
1) ioctl to make sure all VGA devices are disabled and remember the one
that was. It uses kernel calls to achieve this.
2) after disabling VGA devices run the user space reset program which
will enable VGA on the card being reset
3) ioctl the driver again to disable all VGAs and restore the original
one.

I think it would be better to just get the whole reset issue out of
xfree and into a separate hotplug app. fbdev needs reset support too.



> > 3. Borrowing things like BIOS mode switch functionality is going to
> > get really hairy.
> 
> But may well be necessary for the forseeable future -- Intel has no 
> current plan to document the i810 (et al) mode selection code, so
> we're 
> stuck with using the BIOS.
> 
> Seems like we need some level of kernel arbitration to keep the
> system
> stable; it could be as little as some PCI remapping ioctls and a
> little 
> lock for shared regions.

Xfree should never remap anything in PCI space. Moving things in PCI
space almost guarantees that a later hotplug event will mess up the
system. Moving things in PCI space should be done with kernel
utilities, not as part of Xfree.

> 
> -keith
> 
> 
> 

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=====
Jon Smirl
jonsmirl at yahoo.com


		
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