Re: Quick question about libata and hdparm

["Rogério Brito" <rbrito@ime.usp.br>]

Hi, Alan. Thanks for your mail.

On Apr 20 2009, Alan Cox wrote:
> > Can you comment on the dmesg log attached? I'd like to, at least,
> > understand what is happening, since I'm starting to consider using
> > libata with all my computers.
> 
> Its logging a couple of transmission errors. The CRC is computed by
> hardware each end and compared (by hardware).

Right. I don't remember the kernel logging out errors when I was using a
custom kernel and pure Debian userland with the promise IDE controller
on this ASUS K7V motherboard (which has a VIA KT-133 chipset, not a
KT-133A).

I can try to test that again, but now I have installed Ubuntu for my
girlfriend. I have two spare IDE HDs here that I can use for testing
purposes and trash everything. If more testing is desired, please let me
know.

> > This computer, in particular, uses an IDE drive with a 40 ribbon
> > cable (and, thus, no UDMA/66). The cable is well put (checked two
> > times already) and I believe that everything is OK with this cable,
> > since I substituted it was already substituting one that gave me the
> > same results.
> 
> It's tuned down to UDMA33 which looks correct.

Yes, that looks fine, as I only have the 40 ribbon cable.

> If I saw a lot of these I'd suspect something like a controller timing
> setup error, but you seem to just have occasional ones in the log which
> really does look like genuine CRC errors from electrical noise or
> similar.

Hummm, now that you mention it, I will see if the loudspeakers installed
may have any impact on it.

> You don't happen to have any amateur radio transmitters or telsa coils in
> the room with it ;) ?

No, I don't. :-) But I do have an open embedded computer (with its own
IDE HD) at less than 10cm of this desktop and said speakers. I will try
to find any other source of electromagnetic noise.

I can try many things here to try to fix that. I want libata to not have
that experimental warning for IDE devices.


Thanks, Rogério Brito.

-- 
Rogério Brito : rbrito@{mackenzie,ime.usp}.br : GPG key 1024D/7C2CAEB8
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