Date: Thu, 21 Jul 2005 11:12:50 +0200 From: "Norbert Koch" <NKoch@demig.de> To: "Warner Losh" <imp@bsdimp.com> Cc: freebsd-small@freebsd.org, non_secure@yahoo.com Subject: RE: DMA disable for sandisk CF cards ? Message-ID: <000201c58dd4$5e114360$4801a8c0@ws-ew-3.W2KDEMIG> In-Reply-To: <20050721.020703.41710119.imp@bsdimp.com>
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> > May be, I miss the point. Why do you want to disable > > dma on the cf card, when you can instruct FreeBSD > > to just not use dma (atacontrol(8)) ? > > Because newer CF cards, like the SanDisk, negotiate DMA with the > controller. However, most of the IDE <-> CF Adapters aren't properly > wired for this, as they only implement CF 1.5 and not CF 2.0. So, > when FreeBSD goes to access the device, you get all kinds of timeout > errors. If you are lucky, ata will failback to PIO mode. Most of the > time it has bitten me, I've not been lucky :-(. > > hw.ata.ata_dma=0 is the magic. You can set it at the boot loader > prompt, or you can add it to /boot/loader.conf. atacontrol is way too > late, since this disabling must be done prior to geom's scan for root > (or the moral equivalent in 4.x). Ok, I understand. But you can't do that selectively on a per-device basis, can you? Norbert
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