We are trying to test 64-bit PCI DMA for a SCSI driver on a Xeon box,
RH9 2.4.20-8 bigmem kernel, 6GB RAM.
The machine shows 6GB in top, we set highmem_io in the driver, PCI DMA
mask covers 64-bit range, etc.
Of course we're trying to make sure that the system does not create
bounce buffers unnecessarily. On a 64-bit box (AMD64) everything works
as expected. On the Xeon, no matter what we try, we never see I/Os
mapped above 4GB.
Any ideas on how we can drive I/Os mapped above 4GB down to our driver?
Thanks,
-Mark
On Thu, 2003-11-06 at 17:05, Mark Mokryn wrote:
> We are trying to test 64-bit PCI DMA for a SCSI driver on a Xeon box,
> RH9 2.4.20-8 bigmem kernel, 6GB RAM.
> The machine shows 6GB in top, we set highmem_io in the driver, PCI DMA
> mask covers 64-bit range, etc.
can you give an URL to the driver so that we can see why it breaks ?