Re: ISA Lance cards in Alpha AXP boxes

Thomas Bogendoerfer (tsbogend@bigbug.franken.de)
Wed, 8 May 1996 19:06:07 +0200 (MET DST)


> I noticed that somebody sprinkled a few #ifdef __alpha__ through the
> lance driver, to avoid probing for ISA based lance cards. Unless there
> is some fundamental reason why bus-master ISA lance cards don't work on
> AXP boxes that I am not aware of, these architecture based #ifdef
> are not needed (not to mention ugly ;-) and just needlessly stop AXP
> people from using these ISA cards.

there is a good reason. In the current Alpha kernel setup there is no
DMA PCI->Host mapping for the ISA address space. So you can't do any
busmastering on the ISA bus of an alpha machine. What's needed is
support for DMA Scatter/Gather similair to the VDMA stuff in Linux/Mips.
I was thinking of adding some code, but I didn't have enough time
to do it.

> I would guess that they were added because someone noticed that
> the ISA probe would cause the alpha to barf. Well, no wonder, with
> lines like:

that was the reason for adding the ifdef around the probe for the
HP lance.

> Rather than use #ifdef __alpha__ it makes more sense to do what I did for

ok, I will change that.

Thomas.

-- 
That process _deserves_ to die ("My name is Linus Torvalds, prepare to 
die").                                [Linus Torvalds on linux-kernel]