I've been playing with libata on a few machines and I found that this machine (An old Dell Dimension L866r) gives me this when it loads and does not give me access to the cdrom. This is the only machine that I've tested that I know for a fact cannot do DMA on the cdrom. I searched and noticed a similar problem with 2.6.19-rc versions but I'm not sure if it's the same problem.
dmesg output: libata version 2.00 loaded. ata_piix 0000:00:1f.1: version 2.00ac7 PCI: Setting latency timer of device 0000:00:1f.1 to 64 ata1: PATA max UDMA/66 cmd 0x1F0 ctl 0x3F6 bmdma 0xFFA0 irq 14 ata2: PATA max UDMA/66 cmd 0x170 ctl 0x376 bmdma 0xFFA8 irq 15 scsi0 : ata_piix ata1.00: ATA-4, max UDMA/33, 10018890 sectors: LBA ata1.00: ata1: dev 0 multi count 16 ata1.00: configured for UDMA/33 scsi1 : ata_piix ata2.00: failed to IDENTIFY (I/O error, err_mask=0x1) scsi 0:0:0:0: Direct-Access ATA QUANTUM FIREBALL A08. PQ: 0 ANSI: 5 lspci on the ide controller: 0000:00:1f.1 0101: 8086:2411 (rev 02) (prog-if 80 [Master]) Subsystem: 8086:2411 Flags: bus master, medium devsel, latency 0 [virtual] Memory at 000001f0 (32-bit, non-prefetchable) [disabled] [size=8] [virtual] Memory at 000003f0 (type 3, non-prefetchable) [disabled] [size=1] [virtual] Memory at 00000170 (32-bit, non-prefetchable) [disabled] [size=8] [virtual] Memory at 00000370 (type 3, non-prefetchable) [disabled] [size=1] I/O ports at ffa0 [size=16] The cdrom is a Lite-On LTN483S - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/