[ltp] T30 "ide: Assuming 33MHz system bus speed for PIO modes ; override with idebus=xx"

[Allen, Michael B (RSCH)]

> -----Original Message-----
> From:	Ben Pfaff [SMTP:blp@cs.stanford.edu]
> > I have another question. On boot I get the the following message:
> > 
> >   ide: Assuming 33MHz system bus speed for PIO modes; override with idebus=xx
> > 
> > I am MUCH more concerned with reliability so I'm in no hurry to mess with idebus
> > kernel parameters but I'm curious; is this message just paranoia? If so what can I
> > safely set the parameter to?
> 
> A comment next to that message in the kernel source says that 33
> is a "safe default value for PCI".  I take that to mean that
> changing it would act only as an optimization.
> 
> This might not even mean anything: chances are that PIO modes are
> unused in favor of DMA, though I haven't checked.
> 
	I think your right. I don't see any drivers that try to actually set idebus_speed derived
	timings and here's a relevant lkml post:

	  http://www.uwsg.iu.edu/hypermail/linux/kernel/0101.3/0221.html

	The driver specific ide0=xxx parameters sound more meaningful. Just as a reference,
	on my Dell Precision 410 at work I get the following with hdparm:

	  [root@miallen3 root]# hdparm -tT /dev/sda

	  /dev/sda:
	   Timing buffer-cache reads:   128 MB in  0.92 seconds =139.13 MB/sec
	   Timing buffered disk reads:  64 MB in  2.72 seconds = 23.53 MB/sec

	I'll see what I get on the T30 when I get home.

	Thanks,
	Mike