The hardware:  UP1000 Alpha, with ALI M1543C IDE.  Fujitsu 2GB udma33
drive, I think.  ATAPI UDMA CDROM.

The problem:  2.2.15 (as packaged with MDK 7.1 for Alpha) works fine. 
2.4.current, both ac tree and linus tree, fail to work at all.  I've
tried all combinations I can think of, for: with and without the
alim15xx.c driver, with/out IDEDMA, with/out IDEDMA on auto, with/out
"ide=nodma" on cmdline.

2.2.x gives the message "DMA disabled (BIOS)", and tunes the drives for
PIO.

2.4.x, even with "nodma", tunes the hard drive and CDROM drive for
udma.  All hard drive accesses fail with "hda: lost interrupt" and "hdc:
lost interrupt".  With the attached patch, it no longer appears to tune
the drives for UDMA, but I still get lost interrupt messages and no
usable drives.

-- 
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Building 1024    | "I'm extremely serious about nailing your
MandrakeSoft     |  step-daughter, but other than that, yes."