daniel sheltraw wrote:
>
> Hello realtimers
>
> My understanding of shared memory under RT Linux is that it uses
> vmalloc to allocate memory and therefore this memory may not be
> suitable for DMA (the memory is not guaranteed contiguous).
>
> (1) Is this the truth, the whole truth and nothing but the truth?
Yes it is true, but I think there is a way to make it DMA safe in the
upcomming 2.4 kernels.
> (2) Is there someway to use the shared memory implementation in a
> manner suitable for DMA?
Use the old style method of append="mem=xxxm" in your lilo.conf to
reserve some high memory and then use mmap in userland (using /dev/mem)
and ioremap in the kernel giving both the fixed address of the reserved
memory.
Regards, Stuart
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