Re: dri and udev

[Jon Smirl <jonsmirl@yahoo.com>]

The new DRM module has other changes in it so it has to be sync'd with a
DRI/Xfree86 release.  I also have to get the changes coordinated with the BSD
DRI people. DRM development happens out of the DRI tree not the kernel tree. So
after there is a DRI/Xfree86 Linus moves the changes over to the copy in the
kernel.

Another issue is the current conflict between fbdev and dri. Both device drivers
are trying to take overship of the graphics hardware. Right now fbdev owns the
hardware and DRI operates as a stealth module. For sysfs/udev to work DRI has to
have a PCI ID table and own the hardware. Doing this prevents fbdev and DRI from
simultaneously being loaded. 

This conflict has not been resolved. We did a previous version of DRM which
registered with the kernel as owning the hardware and got a lot of vocal
complaints from fbdev developers. DRM was backed off into steath mode again.

Stealth mode looks like this. It never calls pci_register_driver so the kernel
never knows that DRM has attached to the device.

static int __init drm_init( void )
{
	struct pci_dev *pdev = NULL;

	DRM(parse_options)( drm_opts );
	DRM(mem_init)();

	while ((pdev = pci_find_device(PCI_ANY_ID, PCI_ANY_ID, pdev)) != NULL) {
		DRM(probe)(pdev);
	}
	return 0;
}

My personal opinion on this is that it is insane for two device drivers to be
trying to share the same same piece of hardware - it's multitasking for device
drivers. I also don't think udev/sysfs are set up to deal with two device
drivers claiming the same piece of hardware.


==Jon Smirl
jonsmirl@yahoo.com

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