Re: mm and DMA devices

Jens David (dg1kjd@afthd.tu-darmstadt.de)
Thu, 21 Oct 1999 20:43:24 +0200


Hi,

Alan Cox wrote:
>[...]
> The buffer you are given isnt going anywhere until you free it.

Sorry, my mistake, I was really free()ing it up before.

> For PCI if your hardware is ok then you can hit the full 4Gig and are fine.
> Remember to check alignment rules. Some hardware has problems with
> alignment and you may have to make aligned copies at times.

I know. This was the issue wi the Realtec 100Mbps ether chipset.
Fortunately I do not have _these_ problems, but I know my next projects
will use only Zilog products instead...

What is this GFP_DMA32 thing? As of 2.2.13ac14 I could not find any
definition nor reference.

For the future I have a suggestion. Someone really ought to write
something about memory allocation like Linus did for IO-mapping. This
would really be very helpful.

-- Jens

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