Re: pci_read_config_byte in 2.1.85

Martin Mares (mj@atrey.karlin.mff.cuni.cz)
Thu, 5 Feb 1998 11:49:17 +0100


Hi,

> Be careful of hiding the real world from programmers too much. I think
> what you propose is fine, especially since it allows the pcibios_*
> functions to continue to exist unaltered.

Well, I propose not using (or even removing) the pcibios_find_something
functions as they are offering less functionality with a more complex interface
and they are usually implemented by walking the same pci_dev list.

> Now as for the matter of the IRQ value in the PCI configuration space and
> its applicability to the kernel world, well, that is what it exists for.
> It turns out that the interrupt number in the configuration space is
> strictly a means for a BIOS to communitate IRQ assignment to the O/S. I do
> not believe that the board is even allowed to look at the number contained
> therin.

You're right, the number has no significance for the card, but we cannot
store the real IRQ here since the IRQ number is an int, not a byte (more than
8 bits are used on the Ultra). Similar problems have arosen with the base addresses
as you can have machines with multiple PCI busses.

Have a nice fortnight

-- 
Martin `MJ' Mares   <mj@ucw.cz>   http://atrey.karlin.mff.cuni.cz/~mj/
Faculty of Math and Physics, Charles University, Prague, Czech Rep., Earth
"How do I type 'for i in *.dvi do xdvi $i done' in a GUI?"