From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <8c0e2e9fc0c571f3be800e7c21531f11@quanstro.net> From: erik quanstrom Date: Tue, 5 Aug 2008 15:49:38 -0400 To: 9fans@9fans.net MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Subject: Re: [9fans] Bizarre freeze Topicbox-Message-UUID: fba786c2-ead3-11e9-9d60-3106f5b1d025 > > I wonder why there is a command to turn on DMA on disks. Could > > it be that some disks don't work with DMA on? > sure. it's PC hardware, so it's crap :-) unfortunately, this isn't a pc hardware thing. pata devices are not required to support dma. ata 7, which is the first to include sata support, requires udma mode 5 support. (many sata:pata bridges violate this part of the spec, e.g. sata doms.) but i'm wondering if dma support isn't a red herring. > sdC0 is a cdrom. I can turn dma on for my sata disks (sdE0/sdF0) no problem. it could be that this is a chipset that advertizes sata and pata pci devices concurrently, but only one may be accessed by the operating system. some ich 7 chipsets fall into this category. does this also hang your machine? echo probe|scuzz if so, i would put some debugging in atapktio. otherwise, it just might be a bug in sdata.c - erik