Re: [debian-knoppix] nodma as a more common option
Hi,
On Sat, Dec 11, 2004 at 01:15:59AM -0800, Stephen Samuel wrote:
> I think that NODMA should be either set as the default option
> (again), or it's use should be more strongly suggested.
I don't think so. Most problems are not because dma acceleration is
applied as default, but because dma acceleration is *forced* on all
chipsets/drives. For example standart debian kernel has enabled dma
acceleration as default, but chipsets/drives are checked for DMA support
during bootup and DMA is enabled only on supported chipsets/drives. So,
DMA in knoppix should be enabled in kernel config, like in standard
debian kernels and then there would be less problems, than forcing dma
in startup scripts.
One more problem with dma is in CD drives, some CD drives don't work
well in dma mode, even when systems chipset and hard drives support dma
without problems. So, It would be wise to have an option to disable DMA
only for CD drives
> Recently, I've run into a good number of machines (P2 and up)
> which fail to boot properly unless nodma is specified. I now
> specify nodma in the isolinux.cfg when I rewrite knoppix
> CDs ( I still haven't tried remastering the compressed
> filesystem)
Which problems do you meet ? could you write the error messages to the
mailing list ?
> Im thinking that the use of nodma should be suggested as the
> first line of defence when a recent version of knoppix won't
> boot plainly.recent versions of knoppix.
>
> Other than that, perhaps some sort of test chould be created
> which recognizes if a disk/controller flakes during boot with
> DMA on, and reverts to nodma. (is it possible to set the kernel
> boot paramaters (/proc/cmdline) after the system is partway thru
> booting??)
AFAIK linux kernel could do these tests during booting.
--
Good luck,
Mantas Kriaučiūnas <mantas@akl.lt> Jabber ID: mantas@akl.lt
Public organization "Open Source for Lithuania" - www.akl.lt
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