From owner-freebsd-hackers  Wed Nov 26 02:34:27 1997
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Subject: Re: PIIX configuration
In-Reply-To: <19971126100027.53229@mail.award.de> from "tg@award.de" at "Nov 26, 97 10:00:27 am"
To: tg@award.de
Date: Wed, 26 Nov 1997 11:31:13 +0100 (MET)
Cc: hackers@FreeBSD.ORG
From: Søren Schmidt <sos@FreeBSD.dk>
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In reply to tg@award.de who wrote:
> Hello all,
> while looking through the source in /sys/pci yesterday, I noticed that the
> detection code for the Intel 82371xx IDE chip (PIIX) was present in 2 places.
> 
> The detection code in pcisupport.c will find the chip first, claim it and
> display that it found one, but will not do anything with the chip.
> 
> This effectively blocks the detection code in wd82371.c, which means that the
> more sophisticated code there does not get executed at all, so no DMA setup.
> Quite a pity if your IDE disk supports DMA.

You must be looking at a 2.2.x system.
For more up to date (E)IDE  driver system look in curent, there is
suppport for DMA etc modes.

> As I was playing around (OK, hacking around) in the wd PCI interface stuff
> trying to speed up my IDE disk (it's nearly 3 times faster when using Linux,
> but I want to run FREEBSD), I wondered if there was any sound technical reason
> behind this ?

Most of the speed difference comes from the fact that linux has delayed
write on as default, try mounting your disks with the async flag, and
you will see semilar performance (and less security against corrupted
disks on power outages etc).


-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Søren Schmidt               (sos@FreeBSD.org)               FreeBSD Core Team
                Even more code to hack -- will it ever end
..