It seems to be something to do with the compression/decompression of the
drive. It seems almost 8 times faster to use 64kb blocks than 4kb
blocks to transfer the same data.
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...
> > And I was happy...But then I ran the exact same command again and the
> > machine froze hard (even interrupts were dead -- no sysreq). So, is this
> > not possible? Is there another workaround that could be done? Is there
> > just a dumb bug in my patch (attached)?
>
> I'm guessing your SCSI controller just DMA'd over the top of something
> critical (kernel code, page table, ...).
Yeah...Probably. I was expecting this to happen anyway, but the fact that
for the three times I tested it it worked flawlessly the first time and
locked up the next time was confusing me. :)
Hmm...Maybe I could make it free lots and lots of memory until it can find
a big enough contiguous region...
Simon-
| Simon Kirby | Systems Administration |
| mailto:sim@netnation.com | NetNation Communications |
| http://www.netnation.com/ | Tech: (604) 684-6892 |
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