[mythtv] "Strange Error Flushing Buffer" problem

Ray mythtv-dev@snowman.net
Wed, 18 Dec 2002 08:51:19 -0700


On Tue, Dec 17, 2002 at 06:37:49PM -0500, Richard Bowman wrote:
> 
> I guess I've just got this computer too maxed out. I truly thought once
> we got rid of ISA slots that IRQ problems weren't an issue.

Well there is no way to get rid of ISA in a PC.  The plastic slots can be
left off but the rest of it is still there.  PCI has to some extent made
IRQs a non-issue since it makes it safe and easy (on the hardware side) for
devices to share IRQs.  The drivers however need to be written to deal with
this properly and not all are.

> Windows seems to reassign devices to IRQs much higher in number than the
> first 15. I thought I'd seen Linux do this as well in its bootup, but I
> don't seeing remember RedHat 8 doing it, which I have now.

I'm not sure what's really going on when the OS claims to be assigning IRQs
higher than 15 but the fact is that consumer motherboards only have 4 real
interrupts avilable to all PCI devices (which includes most of the
integrated stuff) so sharing is inevitable.

> I'm going to update the MB's BIOS, so I can hopefully have a bit more
> control over the IRQ's.

It's not going to help.  The IRQs are tied to the slot the device is
attached to.  If, for example, you have slot 1 & 2 sharing IRQ 10 you may be
able to change that to IRQ 5 but they will still be sharing.  If you have a
device whos' driver doesn't share properly the only options are to replace
the device, move it to another slot, or find a better driver.

-- 
Ray