Re: How to Switch DMA off for only one Harddisk at Kernelboot

Alan Cox
2007-12-16T20:23:25Z

On Sun, 16 Dec 2007 19:06:04 +0100
Oliver Joa <oliver@j-o-a.de> wrote:

> Hi,
>
> how can I tell the kernel not to probe DMA for a specific harddisk (e.g.
> hda). My first Drive (hda) is a Compact-Flash Card which can not do DMA.
> The kernel tries at boot to switch to DMA but fails. If I use ide=nodma,
> the kernel boots about 2 minutes faster, but then I can not switch on
> DMA for the second Drive (hdc) which is a normal Harddisk. Do I have to
> live with this 2 minutes waiting time or is there another solution? I
> did not find any kernel-parameter for this purpose.
>
> Sorry if I ask here, but I can not find any solution, and I asked
> already in other groups.

For the current kernel and libata you can use libata.dma=3, and it will
select DMA for disk (1) + CD (2) but not CF cards. With the older IDE it
should be sufficient to use hda=nodma

Alan