HEADS UP: Check your devices' UDMA settings - *TEMPORARY* *WORKAROUND*

[Basil Chupin]

On 05/04/2011 15:51, Basil Chupin wrote:
> It appears that Bug #195221 has suddenly come back -- see 
> https://bugs.launchpad.net/ubuntu/+bug/195221.
>
> This bug re-appeared on 1 April (my time, Australia, East Coast) 
> because the previous day my logs showed that the UDMAs were being set 
> correctly. The only thing which I can see is that on 1 April there was 
> a kernel firmware upgrade but as I know nuffin' about kernels (or 
> majors or even captains) this upgrade may have nothing to do with it.
>
> What the above Bug is about is that even though your HDD, for example, 
> can do UDMA 133 the UDMA in fact gets set to UDMA 33 because some 
> check concludes incorrectly that the device is connected with a 
> 40-wire cable. Here is an example I just took from my dmesg log file:
>
[pruned]

The temporary workaround for this problem is to add to the boot 
parameters the following: libata.force=X:80c

where X is the IDE line which is being affected by this UDMA problem. In 
my case, the devices on line #2 are affected so I use libata.force=2:80c 
and now the HDD and the DVDRW are being set to UDMA 100 & 100, respectively.

Using 'libata.force=X:80c' is working because libata is actually 
statically embedded in the kernel; if it was not then you would use 
'force=X:80c'.

(Now I have to go and read up on grub 2 to see how I can insert this 
workaround in grub without having to add this everything to the boot 
parameters at boot time.)

BC


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