turning DMA on with hdparm

geniarse · 09-07-2004, 04:00 PM

I'm trying to turn dma on for my cd-roms (for nice fast dvd access). I am pretty certain the drive supports dma as is nice and new (is there any way to find this out). however when I run (as root)

Code:

hdparm -d1 /dev/hdb

I get told:

Code:

/dev/hdb:
 setting using_dma to 1 (on)
 HDIO_SET_DMA failed: Operation not permitted
 using_dma    =  0 (off)

how come???

Also I read that the kernel does not enable DMA for devices on boot due to compatability reason's. How do I enable this rather than having to use hdparm

geniarse · 09-07-2004, 04:01 PM

just found out how to find whether DMA able using

Code:

hdparm -I /dev/hdb

and the drive is DMA able

Plus I have found out that the drive is using 16bit I/O mode despite being set to 32bit by bios, how come kernel has overwritten this setting

geniarse · 09-07-2004, 04:38 PM

I have solved the problem, I hadn't compiled my IDE controller into the kernel now all drives using DMA (didn't need to post this really took me a further 5 minutes to figure out). However still not using 32 bit IO, any ideas anybody.

Electro · 09-07-2004, 04:48 PM

What does "hdparm -v /dev/hdb" show?

What does "hdparm -v /dev/hd[a-z]" show? (I think you did not compile the kernel for DMA support)

What brand and model is your DVD drive?

geniarse · 09-09-2004, 03:47 PM

I have solved the DMA problem, It's not that I hadn't compiled DMA into kernel, I compiled the incorrect IDE controller chipset, so hdparm wasn't accessing it correctly (hence the failure). I have already explained this in previous post, but thanks for the help anyway.