The 03.05.03 at 23:30, H du Plooy wrote:
What I didn't understand was that DMA needed to be enabled for the corresponding /dev/hdx device - I didn't know you could do that. Found that out thanks to a typo, and now all is fine. I can burn at any speed, and CPU usage remain low (althoug still higher than in windows).
Ah! :-O Yes, out of curiosity, I just reviewed that conversation, and it seems nobody told you that explicitly. It's a question many times asked, so we didn't explain it fully... curious.
so the kernel is a ware of the DVD and CD-RW drives' DMA capabilities. Why doesn't it enable it by default?
Good question. Probably because sometimes it may not work.
Is there a bootparameter that will tell the kernel to switch it on? This would help with installations! (see my other post)
Er... there is an option on the sources to turn it on by default if available. Let me see... here, this is how the kernel is set up: ATA/IDE/MFM/RLL support ---> IDE, ATA and ATAPI Block devices ---> [*] Use PCI DMA by default when available [*] Enable DMA only for disks Default is no, no; but suse uses yes, yes. If I understand correctly, it means that normal ide devices will have dma on, other devices (like cdroms) will have it off. Probably because it is safer, meaning that it will work on most computers. As for a boot parameter, yes: ide?= [HW] (E)IDE subsystem : config (iomem/irq), tuning or debugging (serialize,reset,no{dma,tune,probe}) or chipset specific parameters. But I think it is for the bus. not the device. In suse 8.1, just edit "/etc/sysconfig/hardware" like this: DEVICES_FORCE_IDE_DMA_ON="hdc hdd" And they will be set on for you. -- Cheers, Carlos Robinson