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

Gabriel C
2007-12-16T19:45:55Z

Oliver Joa wrote:
> Hi,
>
> Gabriel C wrote:
>> Oliver Joa wrote:
>>> Hi,
>> Hi Oliver ,
>>
>>> 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.
>>>
>>> Thank you very much
>> Should work with hda=nodma or ideX=nodma ( where X is your HDD nr , in your case is 0 )
>
> I tried this already, it does not work.
>
>> Also have a look at Documentation/ide.txt.
>
> I read this already. Searching for "nodma" in this document gives only
> one line:
>
> "ide=nodma" : disable DMA globally for the IDE subsystem.
>
> If the documentation is correct hda=nodma and ideX=nodma should not
> work. I use kernel 2.6.23.1 at the moment.

grep nodma Documentation/ide.txt
"hdx=nodma" : disallow DMA

ide=foo_option is for the whole ide sub-system where ideX|hdX=foo_option is just for that HDD.

Anyway I've CC'ed linux-ide.

>
> Thanks
>
> Olli
>

Gabriel