The machine is an Athlon64 laptop with a K8T800 chipset. With the IDE VIA driver the disk is detected as udma/100: VP_IDE: IDE controller at PCI slot 0000:00:11.1 ACPI: PCI Interrupt Link [ALKA] disabled and referenced, BIOS bug ACPI: PCI Interrupt Link [ALKA] BIOS reported IRQ 0, using IRQ 23 ACPI: PCI Interrupt Link [ALKA] enabled at IRQ 23 ACPI: PCI Interrupt 0000:00:11.1[A] -> Link [ALKA] -> GSI 23 (level, low) -> IRQ 17 VP_IDE: chipset revision 6 VP_IDE: not 100% native mode: will probe irqs later VP_IDE: VIA vt8235 (rev 00) IDE UDMA133 controller on pci0000:00:11.1 ide0: BM-DMA at 0x1ce0-0x1ce7, BIOS settings: hda:DMA, hdb:pio ide1: BM-DMA at 0x1ce8-0x1cef, BIOS settings: hdc:DMA, hdd:pio Probing IDE interface ide0... hda: TOSHIBA MK6021GAS, ATA DISK drive hda: selected mode 0x45 ide0 at 0x1f0-0x1f7,0x3f6 on irq 14 Probing IDE interface ide1... hdc: TOSHIBA ODD-DVD SD-R6372, ATAPI CD/DVD-ROM drive hdc: selected mode 0x42 ide1 at 0x170-0x177,0x376 on irq 15 hda: max request size: 128KiB hda: 117210240 sectors (60011 MB), CHS=65535/16/63, UDMA(100) hda: cache flushes supported hda: hda1 hda2 hda3 hda4 < hda5 hda6 hda7 hda8 hda9 > However, the libata pata_via driver complains about the cable and drops the disk to udma/33: pata_via 0000:00:11.1: version 0.3.1 ACPI: PCI Interrupt Link [ALKA] disabled and referenced, BIOS bug ACPI: PCI Interrupt Link [ALKA] BIOS reported IRQ 0, using IRQ 23 ACPI: PCI Interrupt Link [ALKA] enabled at IRQ 23 ACPI: PCI Interrupt 0000:00:11.1[A] -> Link [ALKA] -> GSI 23 (level, low) -> IRQ 17 scsi0 : pata_via scsi1 : pata_via ata1: PATA max UDMA/133 cmd 0x000101f0 ctl 0x000103f6 bmdma 0x00011ce0 irq 14 ata2: PATA max UDMA/133 cmd 0x00010170 ctl 0x00010376 bmdma 0x00011ce8 irq 15 ata1.00: ATA-5: TOSHIBA MK6021GAS, GA024A, max UDMA/100 ata1.00: 117210240 sectors, multi 16: LBA ata1.00: limited to UDMA/33 due to 40-wire cable ata1.00: configured for UDMA/33 ata2.00: ATAPI: TOSHIBA ODD-DVD SD-R6372, 1030, max UDMA/33 ata2.00: configured for UDMA/33 scsi 0:0:0:0: Direct-Access ATA TOSHIBA MK6021GA GA02 PQ: 0 ANSI: 5 sd 0:0:0:0: [sda] 117210240 512-byte hardware sectors (60012 MB) sd 0:0:0:0: [sda] Write Protect is off sd 0:0:0:0: [sda] Mode Sense: 00 3a 00 00 sd 0:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA sd 0:0:0:0: [sda] 117210240 512-byte hardware sectors (60012 MB) sd 0:0:0:0: [sda] Write Protect is off sd 0:0:0:0: [sda] Mode Sense: 00 3a 00 00 sd 0:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA sda: sda1 sda2 sda3 sda4 < sda5 sda6 sda7 sda8 sda9 > sd 0:0:0:0: [sda] Attached SCSI disk scsi 1:0:0:0: CD-ROM TOSHIBA ODD-DVD SD-R6372 1030 PQ: 0 ANSI: 5 hdparm -i confirms this: with the IDE driver it lists udma5 as the current mode, with pata_via it lists udma2 as the current mode. /Mikael - To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html