ATA code is buggy and slower

[Dong Lin]

My 5.0R kernel complains about "READ timeout" and "resetting" when I try to dd the disk. But everything *works* if I boot the same equipment with 4.5R and 4.7R. It seems that the error can occur on any sector I pick as long as I keep reading it inside a loop, a sign of timing problems.

The 5.0 ATA code is so different that I am not sure where to start. If someone can show me a way to run the 4.7 ATA code under 5.0, I am willing to debug it.

My equipment: Promise ATA66 controller(0x4d38105a r01), WDC WD400BB ATA/100, ATA66 cable.

Also, my simple dd measurements show that performance is going down:

dd if=/dev/ad4 of=/dev/null bs=8m
4.5R: 49 MB/s
4.7R: 39 MB/s
5.0R: does not finish



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