Re: > 1GB on alpha. Patch to 1TB?

Thomas Bogendoerfer (tsbogend@alpha.franken.de)
Mon, 15 Mar 1999 00:24:05 +0100


On Sun, Mar 14, 1999 at 11:02:18AM -0500, Jay.Estabrook@digital.com wrote:
> On Alpha, in addition to the direct-map DMA windows which are currently
> used, one can define what we call "scatter-gather" DMA windows. The range of

what I'm wondering for quite a while, why does the DMA window start at 1GB
(2GB with Richard's patch) and not starting from address 0 (so we could make
it up to 4GB). Is this a hardware restriction (couldn't find anything in the
LCA documention) ?

I've tried to set the window base to 0 on my noname, but it didn't work so
well (console was really messed up and it looked like I've got some oopses).
I haven't expected that behaviour (crashing, when doing first PCI bus master
access, would be more reasonable), so I'm not sure whether it's impossible
or just a bug anywhere.

Thomas.

-- 
   This device has completely bogus header. Compaq scores again :-|
It's a host bridge, but it should be called ghost bridge instead ;^)
                                        [Martin `MJ' Mares on linux-kernel]

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