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SubjectRe: UDMA issues under 2.2.3
On Tue, 23 Mar 1999, Mark Lord wrote:

# You need to run this command immediately: "man hdparm"

Ok. It says basically what its always said. With additions for UDMA stuff.

# > root(2)@neko [104 /usr2/root] # hdparm -I /dev/hda
#
# Bzzt! Wrong. Try: hdparm -d /dev/hda

Ok. This tells me its using DMA. It doesn't comment on which MODE of dma
(or udma) it is in. How is this what I wanted? I mean, I was looking for
information on the current UDMA modes that my drives are in. I probably am
mistaking, but the dma in "hdparm -d" is a different monster entirely than
the UDMA I'm speaking about. I thought UDMA (in this context) simply
refered to modes that are brothers for the various PIO modes.

How does "hdparm -d /dev/hda" fit into that?

# Ignore that error -- triggered by hdparm, so it's really self-inflicted.
# And totally harmless.

Ok, cool.

# > hdparm -X66 /dev/hda
# >
# > my system will crash within seconds.

# You should not be playing with those options.
# Or at least do "man hdparm" first, and read the output thoroughly.

Ok, so I guess I'm missing something here. Perhaps my original question
wasn't phrased correctly, or I simply am speaking mush. Let me try again.

""
1. Why does hdparm report all my drives in UDMA mode2 when I have it
disabled in BIOS and have CONFIG_IDEDMA_AUTO disabled? Is it the default
on the drives THEMSELVES? Then what effect does BIOS have on this? None?

2. If the drives are infact in UDMA mode2, why does hdparm -X66 crash my
system. Does that command not say to put the drives in UDMA mode2?

3. How does one disable UDMA but keep DMA enabled? For example, if I just
wanted to use DMA multiword mode 2? According to man,
hdparm -X34 /dev/hda
should do it. But if I do that, my system locks up immediately with a
"can't get DMA for /dev/hda" or somesuch. Shouldn't my drive support
mword2 if it supports UDMA mode 2? (btw...

PIIX4: IDE controller on PCI bus 00 dev 39
PIIX4: not 100% native mode: will probe irqs later
ide0: BM-DMA at 0xffa0-0xffa7, BIOS settings: hda:DMA, hdb:DMA
ide1: BM-DMA at 0xffa8-0xffaf, BIOS settings: hdc:DMA, hdd:pio
hda: WDC AC36400L, ATA DISK drive
hdb: IBM-DTTA-351010, ATA DISK drive
hdc: WDC AC36400L, ATA DISK drive
hdd: NEC CD-ROM DRIVE:260, ATAPI CDROM drive
ide0 at 0x1f0-0x1f7,0x3f6 on irq 14
ide1 at 0x170-0x177,0x376 on irq 15
hda: WDC AC36400L, 6149MB w/256kB Cache, CHS=13328/15/63
hdb: IBM-DTTA-351010, 9671MB w/466kB Cache, CHS=19650/16/63
hdc: WDC AC36400L, 6149MB w/256kB Cache, CHS=13328/15/63

According to specs, all my drives support UDMA mode 2).

4. So I gues the question is, why can't I tweak any of the drives? Why
cant I put them in UDMA mode 2 when they say they already are? Why can't I
put them in DMA mode 2 without crashing my system?


# --
# mlord@pobox.com
#


G'day! <i didn't think i got a pleasant answer>
-- n i c h o l a s j l e o n
elegance through simplicity*http://mrnick.binary9.net*nicholas@binary9.net
good fortune through truth*roaming:njllm@email.msn.com*ICQ#2170994*U+($++)
TRA#6805*not all questions have answers*pseudogeek:P+++($++)L+($++)W=lm@b9
2.3x10e-53*seek the path-not the destination*madison*pain builds character


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