# dma w/ hdparm on cdrom's w/ ide-scsi & proper udma4 on h

## zen_guerrilla

Hello all,

i have an ide dvd-rom (hda) & an ide cdrw (hdc) and I have them both declared as ide-scsi to burn/copy-on-the-fly cd's.

My problem is that hdparm's options don't work with these drives. However they worked fine on my slack & sorcerer installations on the same box.

Hdparm simply tells that '/dev/cdroms/cdromX is not supported'

The options I want are -c1 -d1 for both of them plus -u1 on the cd-rw.

Any idea if this is possible ?

Also my 2nd hd (hdg on a promise 20265) though it supports udma4 hdparm only enables udma2 (options passed : -c3 -d1 -m16). 

How I can force it to use udma4 & is this dangerous after all ?

Thanx in advance

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## dArkMaGE

for turning on udma4 do a search on the forums for hdparm and you should find another article where all the various hdparm options are discussed (its something like hdparm -X 68, but make sure you check the article first)

as to using hdparm on scsi-emulating(ed?) drived you want to use the device file under /dev/ide

youll have to look around a little cuz it depends how your cdrom is attatched, but for my cdrw its /dev/ide/host0/bus0/target1/lun0/cd (which is usually /dev/hdb)

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## zen_guerrilla

Thanx for answering.

I' m checking on udma4 now. But for the ide-scsi cd-rom I have problems. my /dev/ide/hos0/bus0/target... is empty and my drives are only listed as scsi. 

Any other suggestion ?

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## mvo

Hi,

you can create an /dev/hdx entry manually (example for my cdrw with ide/scsi on secondary slave) or edit /etc/devfs.conf for that:

hal9000 dev # mknod -m 660 hdd b 22 64

hal9000 dev # /sbin/hdparm -d1 -c1 -k /dev/hdd

/dev/hdd:

 setting 32-bit I/O support flag to 1

 setting using_dma to 1 (on)

 I/O support  =  1 (32-bit)

 using_dma    =  1 (on)

 keepsettings =  0 (off)

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## zen_guerrilla

This mknod thing seams ok, but I never made any nodes by myself I want a little bit of help. What minor/major & any other options should I use for hda & hdc ?

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## mvo

For major and minor number and type of an device look to "/usr/src/linux/Documentation/devices.txt", the other options "man mknod".

hda: mknod /dev/hda b 3 0

hdc: mknod /dev/hdc b 22 0

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