On Mon, 22 Mar 2010 01:53, Alexander Motin wrote:
In Message-Id: <4ba705cb.9090...@freebsd.org>
jhell wrote:
On Sun, 21 Mar 2010 20:54, jhell@ wrote:
I played with it on one re-compile of a kernel and for the sake of it
DFLTPHYS=128 MAXPHYS=256 and found out that I could not cause a crash
dump to be performed upon request (reboot -d) due to the boundary
being hit for DMA which is 65536. Obviously this would have to be
adjusted in ata-dma.c.
I suppose that there would have to be a better way to get the real
allowable boundary from the running system instead of setting it
statically.
Other then the above I do not see a reason why not... It is HEAD and
this is the type of experimental stuff it was meant for.
I should have also said that I also repeated the above without setting
DFLTPHYS and setting MAXPHYS to 256.
It was bad idea to increase DFLTPHYS. It is not intended to be increased.
I just wanted to see what I could break; when I increased DFLTPHYS it was
just for that purpose. It booted and everything was running after. Wasn't
long enough to do any damage.
About DMA boundary, I do not very understand the problem. Yes, legacy
ATA has DMA boundary of 64K, but there is no problem to submit S/G list
of several segments. How long ago have you tried it, on which controller
and which diagnostics do you have?
atap...@pci0:0:31:1:
class=0x01018a card=0x01271028 chip=0x24cb8086 rev=0x01 hdr=0x00
vendor = 'Intel Corporation'
device = '82801DB/DBL (ICH4/ICH4-L) UltraATA/100 EIDE Controller'
class = mass storage
subclass = ATA
I do not have any diagnostics but if any are requested I do have the
kernel's that I have tuned to the above values readily available to run
again.
The first time I tuned MAXPHYS was roughly about 7 weeks ago. That was
until I noticed I could not get a crash dump for a problem I was having a
week later and had to revert back to its default setting of 128. The
problem I had a week later was unrelated.
Two days ago when I saw this thread I recalled having modified MAXPHYS but
could not remember the problem it caused so I re-enabled it again to
reproduce the problem for sureness.
Anything else you need please address,
Regards,
--
jhell
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