I now enabled IO/APIC in my kernel. See attached .config. I also enabled 
  pata_via but was unsure which IDE driver to disable. The kernel 
rebooted fine. The following appeared in my syslog when the smartctl 
command spinned up the disk:

Feb 19 18:57:09 homemp3 kernel: ata5.00: exception Emask 0x0 SAct 0x0 
SErr 0x0 action 0x6 frozen
Feb 19 18:57:09 homemp3 kernel: ata5.00: failed command: SMART
Feb 19 18:57:09 homemp3 kernel: ata5.00: cmd 
b0/da:00:00:4f:c2/00:00:00:00:00/00 tag 0
Feb 19 18:57:09 homemp3 kernel:          res 
40/00:01:00:00:00/00:00:00:00:00/00 Emask 0x4 (timeout)
Feb 19 18:57:09 homemp3 kernel: ata5.00: status: { DRDY }
Feb 19 18:57:09 homemp3 kernel: ata5: soft resetting link
Feb 19 18:57:09 homemp3 kernel: ata5.00: configured for UDMA/133
Feb 19 18:57:09 homemp3 kernel: ata5: EH complete


At least it seems that the kernel recovered better from this exception 
than before. In particular, IRQ10 didn't get disabled and so I/O 
continued to work fine. Thanks for the hint.

Would you consider the exception above a serious problem that should be 
taken care of somehow?

Best,
-- Axel

Mikael Pettersson wrote:
> Axel Uhl writes:
>  > Here's what /var/log/dmesg contains:
> ...
>  > Tejun Heo wrote:
>  > > Hello,
>  > > 
>  > > On 02/12/2010 05:46 PM, Axel Uhl wrote:
>  > >> I don't have a /var/log/boot.msg, only a /var/log/boot. Its contents:
>  > > 
>  > > Then please attach output of dmesg after boot.
> 
> Judging from your initial message and this one, it appears that the
> problematic disk is driven by sata_via, but sata_via shares IRQ with
> an awful lot of other junk.
> 
> Suggestions:
> 1. Enable IO/APIC support in the kernel. According to your previous lspci
>    the chipset does have one. This should reduce IRQ sharing and make IRQ
>    handling generally better. If there's still some sharing going on,
>    try moving PCI cards to other slots.
> 2. Move the problematic disk around to e.g. the Promise controller. Do the
>    stray exceptions persist? If so, then it's the disk that's at fault.
>    As long as the libata's error handling recovers, things should work anyway.
> 3. (Unrelated but...) Why use Old IDE to drive the VIA PATA controller?
>    Just use pata_via for that one, enable SCSI SR+SG support, and disable IDE.
> 

-- 
Find Security Certificate at http://www.axel-uhl.de/cgi-bin/cacert.cgi