Date: Fri, 13 Apr 2001 05:48:49 +0200 From: "Michael Nottebrock" <michaelnottebrock@gmx.net> To: "brian j. peterson" <rbw@myplace.org>, <freebsd-questions@FreeBSD.org> Subject: Re: turning off DMA pre-boot Message-ID: <012701c0c3cc$a952e260$0508a8c0@lofi.dyndns.org> References: <Pine.BSF.4.21.0104111225540.26386-100000@malkavian.org>
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----- Original Message ----- From: "brian j. peterson" <rbw@myplace.org> To: <freebsd-questions@FreeBSD.org> Sent: Wednesday, April 11, 2001 11:11 PM Subject: turning off DMA pre-boot > background: > > i have a 4.3-BETA system that is freezing on me every few days. (the > cvsup from 4.2-R to stable was done around March 11th.) i have trimmed > down the kernel as much as possible in an attempt to isolate the problem, > but this hasn't helped so far. the motherboard this system is on uses a > VIA chipset, and i have been hearing that VIA's DMA support is less than > perfect. turning off DMA in the BIOS didn't seem to stop FreeBSD from > using DMA (at least according to 'sysctl hw.atamodes'). i was able to > turn off DMA _after_ boot by running 'sysctl -w hw.atamodes=pio,pio,'. (i > just did this last night, so i'm not sure if this has solved the system's > freezing problem.) > > question: > > is there some way to disable DMA support (and force PIO mode) before the > system boots? perhaps a kernel option or a loader option? > > any help would be greatly appreciated. > > thanks for your time, > brian There is, at least in the latest 4.3's. You can set hw.ata.ata_dma="0" in /boot/loader.conf amongst some other options. Turning off dma after booting should have solved your problem, though, if it was really ide-dma related. Also see 'man ata' for details. Greetings, Michael Nottebrock To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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