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[jap1968 <jap1968@xxxxxxxx>]

I am using a modified kernel:

http://www.array.org/ubuntu/features.html

Which includes the 40-wire UDMA patch. I do not know if this same patch
is going to be included in the official kernel, but it seems to work
flawlessly.

Anyway, the speed improvement (Eee PC 701, 4GB) is much less than what I
expected.

-- 
Wrong UDMA mode due to error in 40/80 wire cable detection
https://bugs.launchpad.net/bugs/195221
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Status in Ubuntu: Invalid
Status in “linux” source package in Ubuntu: Triaged
Status in “linux-source-2.6.22” source package in Ubuntu: Won't Fix

Bug description:
I have an Asus Eee PC 4GB laptop, and I am testing Ubuntu Hardy 8.04 (kernel 2.6.24-8) on it.

The computer has a 4GB SSD soldered to the motherboard. The disk is reported as UDMA66 capable, but is installed as UDMA33 because the system does not detect a 80 pin conductor.

I have tried adding kernel parameters (ide0=ata66 ide1=ata66) but these seems to be ignored. I have read that these parameters are just to instruct the kernel not to do the 40/80 wire test.

I have written a blog entry [http://ospatia.blogspot.com/2008/02/eee-pc-optimizar-el-disco-ssd.html] (in Spanish) with additional information (dmesg output, some tests with hdparm, ...) and I have found additioal people having same problem with fast (300x) Compact Flash cards.

dmesg output extract:

[   26.700245] ata2.00: ATA-4: SILICONMOTION SM223AC, , max UDMA/66
[   26.700256] ata2.00: 7815024 sectors, multi 0: LBA
[   26.700297] ata2.00: limited to UDMA/33 due to 40-wire cable
[   26.716208] ata2.00: configured for UDMA/33