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SubjectRe: SCSI tape buffer allocation hitting memory allocation
On Fri, 12 Feb 1999, Simon Kirby wrote:

> Hmm...it makes obvious sense that some sort of transfer from a device to
> physical memory wouldn't be able to go through the page translation on the
> CPU unless the CPU was doing the transfer, so it makes sense that
> vmalloc()ed pages wouldn't work. I wonder what the floppy driver does,
> then...

Okay, now that I've realized my first idea is really dumb, I'd like to
confirm that DMA to an onboard/PCI device does actually work addressing
physical memory > 64MB. Is this true? I changed scsi_init_malloc() to
remove the GFP_DMA flag iff the first allocation w/GFP_DMA fails...it
seems to now work (but obviously it will blow up for ISA cards). Is
GFP_DMA is used anywhere else other than to tell __get_free_pages() to
only allocate in areas < 64MB)? I'm assuming this should be safe (for the
case of this one machine w/no ISA SCSI controllers) if not.
Simon-

| Simon Kirby | Systems Administration |
| mailto:sim@netnation.com | NetNation Communications |
| http://www.netnation.com/ | Tech: (604) 684-6892 |


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