Problem with DMA buffer (in 2.2.15)

From: Christoph Baumann (
Date: Wed Feb 21 2001 - 12:12:34 EST


I have the following problem.
A user process wants to talk to a PCI board via DMA. The first step I did was
to resolv the physical addresses of the data in user space. This works fine
when writing to the device. But when reading the buffer isn't allocated
and the physical addresses are resolved to zero. I fixed this with initializing
the buffer. My question is: Is there a faster method to get the kernel to
map all the virtual addresses at once and not each by each? This would
increase the performance enormously (from 33MB/s to [hopefully] 100MB/s).


* Christoph Baumann                                      *
* Kirchhoff-Institut für Physik - Uni Heidelberg         *
* Mail:                    *
* Phone: ++49-6221-54-4329                               *

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