DOC vs. IDE
Eric W. Biederman
ebiederman at lnxi.com
Mon Sep 30 04:07:01 CEST 2002
"Steve M. Gehlbach" <steve at nexpath.com> writes:
> >> So DoC _IS_ faster than IDE? If this is the case, why should it be
> >> that mounting it with /dev/hda1 as root would make for a faster boot?
> >> By my logic, I would think that having /boot and /root on a DoC would
> >> make it faster.
> >DoC _IS_NOT_ faster than IDE. IDE HD has the problem it need to spin up
> >before taking any command while DoC does not. This spin up time delays
> >you booting speed. On the other hand, once spun up IDE HD is much faster
> >than DoC.
> I've been loading the Linux kernel from CompactFlash (CF) (raw image) in
> /dev/hdc1, and then mount the root disk in /dev/hda1, and this is pretty
> fast. I shortened the delays in the IDE routine since the CF doesn't need
> spin up time. We really need an "intelligent" routine to find when an IDE
> device is ready rather than a pure time delay.
Check the current code in the etherboot source tree. We wait
for the BSY bit to clear before sending commands and it works
fine. Ollie has reported that on some host controllers this doesn't work
but I haven't seen that behavior in practice.
Anyway feel free to send patches...
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