[OLUG] More help with X and i810

[Dave Burchell]

Phil Brutsche says:
> 
> A long time ago, in a galaxy far, far way, someone said...

> > (--)SVGA: PCI: Intel Unknown chipset (0x7121) rev 3, Memory @ 0xe8000000,
> > 0xeff8000
> > (--)SVGA: unable to open /dev/agpgart: no such device
> > 
> > Fatal server error:
> > 
> > /dev/agpgart clearly exists on my machine.
> 
> The Xserver thinks otherwise.

Now, Phil, I must protest.  I have no doubt /dev/agpgart *does* exist
on Kent's machine, and you (and the Xserver) know it full well!  Stop
obfuscating this well-meaning X builder! ;-]

The error "unable to open /dev/agpgart: no such device" does not mean
that the file /dev/agpgart isn't on the system.  It means (as Phil
hints below) that Something Else is wrong.  Loosely, the device file
/dev/agpgart is there, but it isn't communicating with or letting you
open the device driver (kernel module?) that is associated with it.
That's why Phil (quite rightly) says check the modules, check the major
and minor, etc. If you deleted /dev/agpgart and tried the Xserver again
you would likely see a different error message.

There are at least three things you might call "device" here: the file
/dev/agpgart, the kernel component (that could be built as a module)
that you communicate with by opening /dev/agpgart, and the actual
device -- the physical thing in your computer -- you want to use.  If
we were talking serial ports, these three would be (say) (1)
/dev/ttyS0, (2) the "serial" module (that you might see loaded in your
kernel by doing "lsmod"), and (3) a UART on your motherboard that can
be used to spit out and suck up bits via that 9-pin connector on the
back of your machine (and which can communicate with the system via the
system bus).

(If I'm botching this explanation, for God's sake stop me and have
bookpool send me a copy of _Linux Device Drivers_.)

> > Anyone know what is going on here?
> 
> 1) is the agpgart module loaded?
> 2) is the special file /dev/agpgart of the right type (character vs block
> device) and have the correct major and minor numbers?

-- 
Dave Burchell                                          40.49'N, 96.41'W
Free your mind and your software will follow.              402-467-1619
http://incolor.inetnebr.com/burchell/                  burchell at acm.org     

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