>> 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 :-) > ron
the ata spec does not require dma for pata devices. sata, first specified in ata 7, requires udma mode 5, though sata:pata bridges routinely do not. it's impossible to know without a bit more information, but the dma command may be a red herring. > sdC0 is a cdrom. I can turn dma on for my sata disks (sdE0/sdF0) no problem. can you access the cdrom at all? i'm wondering if you're accessing a ahci-capable chipset in ahci *and* ata modes at the same time. - erik
