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Date:      Tue, 5 Jun 2001 08:17:05 -0700
From:      "brian j. peterson" <rbw@myplace.org>
To:        "Thomas T. Veldhouse" <veldy@veldy.net>, freebsd-stable@FreeBSD.org
Subject:   Re: UDMA mode on ATAPI CDROM?
Message-ID:  <20010605081705.C7290@malkavian.org>
In-Reply-To: <002b01c0edc0$955b5b70$3028680a@tgt.com>; from veldy@veldy.net on Tue, Jun 05, 2001 at 08:08:15AM -0500
References:  <Pine.BSF.4.33.0106042255001.73586-100000@fuggle.veldy.net> <20010604232621.A7290@malkavian.org> <002b01c0edc0$955b5b70$3028680a@tgt.com>

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On Tue, Jun 05, 2001 at 08:08:15AM -0500, Thomas T. Veldhouse wrote:
> Thanks.  I wouldn't have known about the man pages as it is not a "device"
> per se and it is not a command.  The sysctl is read only.  It needs to be in
> /boot/loader.conf and a reboot is necessary.

you should be able to change the sysctl value on the fly for at least 
hw.atamodes.  for example,

% sysctl -w hw.atamodes=dma,pio,dma,---,

this would force DMA for the first and third ATA devices and PIO for the
second.  the fourth isn't present, so it gets "---".  i've never tried to
change PIO to DMA for an ATAPI device (like a CD-ROM drive), but i *have*
successfully done it for hard drives without a reboot.  (of course, you
have to be root when running the 'sysctl -w' command.)  ymmv.

<commentary>
too bad they didn't name this sysctl value "hw.ata.modes" to be like the
other hw.ata values.  i suppose there is probably a reason that isn't
readily apparent.
</commentary>

-brian


> ----- Original Message -----
> From: "brian j. peterson" <rbw@myplace.org>
> To: "Thomas T. Veldhouse" <veldy@veldy.net>
> Sent: Tuesday, June 05, 2001 1:26 AM
> Subject: Re: UDMA mode on ATAPI CDROM?
> 
> 
> > read 'man 4 ata'.  it's very helpful.  =)
> >
> > also, 'sysctl hw.ata' will show you the relevant sysctl values.
> >
> > -brian
> >
> > On Mon, Jun 04, 2001 at 10:57:11PM -0500, Thomas T. Veldhouse wrote:
> > > How do I set my ATAPI CDROM to UDMA mode these days?  First it was a
> > > kernel option, then it was an option in /boot/loader.conf, now I can not
> > > find the option at all.  I recall mention of a atactl, but there does
> not
> > > appear to be such a thing in stable.  Can anybody enlighten me on this
> > > puzzling change?
> > >
> > > Thanks in advance,
> > >
> > > Tom Veldhouse
> > > veldy@veldy.net

-- 
--===-----=======-----------=============-----------------===================
|    rbw aka bjp        |        god's final message to his creation:       |
|    rbw@myplace.org    |        we apologize for the inconvenience.        |
===================-----------------=============-----------=======-----===--

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