[techtalk] hdparm and DMA "not permitted"

[James Sutherland]

On Sun, 20 May 2001, Conor Daly wrote:

> Little problem here with hdparm and DMA.  I'm using an AMD K6-2 350MHz on
> some kind of amibios mobo with "Ultra DMA Enabled" in CMOS but I cannot
> set "using dma" for the drive(s).
>
> [root]# /sbin/hdparm -d 1 /dev/hda
>
> /dev/hda:
>  setting using_dma to 1 (on)
>  HDIO_SET_DMA failed: Operation not permitted
>  using_dma    =  0 (off)
>
>
> dmesg returns:
>
> PCI_IDE: unknown IDE controller on PCI bus 00 device 78, VID=10b9,
> DID=5229
> PCI_IDE: not 100% native mode: will probe irqs later
> PCI_IDE: simplex device:  DMA disabled
> ide0: PCI_IDE Bus-Master DMA disabled (BIOS)
> PCI_IDE: simplex device:  DMA disabled
> ide1: PCI_IDE Bus-Master DMA disabled (BIOS)
> hda: Maxtor 91021U2, ATA DISK drive
> hdb: FUJITSU MPD3084AT, ATA DISK drive
> hdc: ATAPI 52X CDROM, ATAPI CDROM drive
> hdd: PHILIPS CDD3610 CD-R/RW, ATAPI CDROM drive
> ide0 at 0x1f0-0x1f7,0x3f6 on irq 14
> ide1 at 0x170-0x177,0x376 on irq 15
> hda: Maxtor 91021U2, 9770MB w/512kB Cache, CHS=1245/255/63
> hdb: FUJITSU MPD3084AT, 8063MB w/512kB Cache, CHS=1027/255/63
>
> Any thoughts?

Enabling DMA requires the right driver in the kernel; there is an option
for "Generic PCI DMA support" or similar, which might be worth a try if
you can't find an exact match for your IDE chipset.

What does /proc/pci have to say about your IDE controller? This should
tell you which driver to use - then just recompile, reboot, and you have
DMA...


James.