Enabling DMA on dvd buerners

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Enabling DMA on dvd buerners

Post by shuiend » Fri Dec 10, 2004 10:57 am

I jus recently switched from slackware to gentoo and I am loving it. So far my only problem is that my ide bus speed is only 33mbs. This is a real pitfall and causing me to only burn cds at 10x and dvd even slower. I have a sata hd so im not worried about that. My dmesg message for the ide bus is as following

ide: Assuming 33MHz system bus speed for PIO modes; override with idebus=xx
NFORCE2: IDE controller at PCI slot 0000:00:09.0
NFORCE2: chipset revision 162
NFORCE2: not 100% native mode: will probe irqs later
NFORCE2: 0000:00:09.0 (rev a2) UDMA133 controller
ide0: BM-DMA at 0xf000-0xf007, BIOS settings: hda:DMA, hdb:DMA
ide1: BM-DMA at 0xf008-0xf00f, BIOS settings: hdc:DMA, hdd:DMA
ide0 at 0x1f0-0x1f7,0x3f6 on irq 14
hda: ATAPI 32X CD-ROM CD-R/RW drive, 4096kB Cache, UDMA(33)
Uniform CD-ROM driver Revision: 3.20
hdb: ATAPI 48X DVD-ROM DVD-R CD-R/RW drive, 2048kB Cache, UDMA(33)

What do I do to move that up to 133mbs like my motherboard can handle?

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Post by Void Main » Fri Dec 10, 2004 11:41 am

You can't set your IDE bus speed to 133 "Mhz" because the IDE speed is only the speed of the PCI bus. For 32 bit PCI the speed should be set to 33Mhz and for 64 bit PCI the speed should be set to 66Mhz. You can try passing "idebus=66" as a kernel parameter and see if it breaks anything but 33 is probably correct. It's more likely a problem in another area, either in the DMA configuration (use "hdparm" command to test/set this) or in your burning application, or your media.

From the "ide.txt" file included in the documentation included with the 2.6 kernel source:

Code: Select all

 "idebus=xx"            : inform IDE driver of VESA/PCI bus speed in MHz,
                          where "xx" is between 20 and 66 inclusive,
                          used when tuning chipset PIO modes.
                          For PCI bus, 25 is correct for a P75 system,
                          30 is correct for P90,P120,P180 systems,
                          and 33 is used for P100,P133,P166 systems.
                          If in doubt, use idebus=33 for PCI.
                          As for VLB, it is safest to not specify it.
                          Bigger values are safer than smaller ones.
Another reference:
http://www.ale.org/archive/ale/ale-2001 ... 00325.html

To check your DMA settings:

# hdparm /dev/dvd

To turn on DMA

# hdparm -d1 /dev/dvd

Setting flags on the command line like this are not permanent. You need to add the settings to your hdparm configuration file for the device you want them to be permanent on. I don't know where this is done on Gentoo. More info on hdparm:

man hdparm

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