On Mon, Feb 17, 2003 at 03:22:43PM +0800, ephemeron@softhome.net wrote:
DMA settings are already enabled on all my IDE disks except for the DVD drive.
[root]# dmesg | grep -i dvd hdc: ATAPI 40X DVD-ROM drive, 512kB Cache [root@gnu root]# hdparm -d 1 /dev/hdc
/dev/hdc: setting using_dma to 1 (on) HDIO_SET_DMA failed: Operation not permitted using_dma = 0 (off)
hum, dma cannot be set ! is this a feature ?
Yes, this is a "feature" of Redhat 8 to "protect" you from yourself. You have to set a special option for ide cdrom in modules.conf to enable dma, then *also* use hdparm. I forget what the option is called; look through the archives. Then mail Redhat and tell them how idiotic they are for doing this!!
I can understand why one might want to disable DMA on a hard disk. I have what appears to be a crappy (or simply too old) VIA-based mobo that produces regular fsck errors when DMA is enabled on the hard drive. But what's the benefit of disabling DMA on a *read-only* CD/DVD drive?
Leave it to the geniuses at RedHat to explain this one to you. :)) Rich