Re: DMA page allocation

Dan Hollis (goemon@sasami.anime.net)
Fri, 18 Jun 1999 19:08:05 -0700 (PDT)

On Fri, 18 Jun 1999, Douglas Gilbert wrote:
> 2 MB may not be enough. Perhaps the DMA buffers size could a
> parameter to the linux kernel and/or a /proc/sys/kernel
> entry as well. It could be scaled up if memory >= 128 MB
> and scaled back if memory <= 24 MB (just guessing ...).

Kernel parameter would be good so that those who dont have ISA can omit
allocations while those with bizarre ISA devices can reserve as much as
they need.

Eg "dmareserve=2m" to reserve 2mb or "dmareserve=5p" to reserve 5% of all
ram (up to the 16mb limit of course).

BTW some PCI devices have arbitrary limits on address registers as well so
on extremely large machines it is possible to still run out of DMA buffers
8)

-Dan

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