Re: Can I get 200M contiguous physical memory?

From: Arjan van de Ven
Date: Thu Mar 10 2005 - 14:31:53 EST

On Thu, 2005-03-10 at 10:57 -0800, Nate Edel wrote:
> From: "Arjan van de Ven" <arjan@xxxxxxxxxxxxx>
> To: "Jason Luo" <abcd.bpmf@xxxxxxxxx>
> >> A data acquisition card. In DMA mode, the card need 200M contiguous
> >> memory for DMA.
> >
> > (or want to reserve memory at the boot commandline and then do really
> > really evil hacks)
> Such as booting the machine with "mem=(real memory - 200)M" and then
> just doing an ioremap of the top 200M of memory.
> It's not the most elegant way of doing things given that it requires
> user intervention at boot time, but I'm not sure it counts as a "really
> evil hack."

it really gets evil if your machine has > 4Gb of ram... then things
really go weird with this.

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