debugging ATA command timeouts on 10.1-RELEASE

[Hans Ottevanger]

On 06/19/15 18:03, Brandon Valentine wrote:
> [ Starting with -hackers before a possible PR. If there's a better place
> for this thread please advise. ]
>
> Howdy,
>
> I have an older Soekris net4801 with a NatSemi SC1100 ATA chipset. Runs
> great under FreeBSD 8.3, but 10.1-RELEASE-p13 spews the following error, in
> a loop, upon boot:
>
> (aprobe0:ata0:0:1:0): ATA_IDENTIFY. ACB: ec 00 00 00 00 40 00 00 00 00 00 00
> (aprobe0:ata0:0:1:0): CAM status: Command timeout
> (aprobe0:ata0:0:1:0): Retrying command
>
> The atapci driver recognizes it as:
>
> atapci0: <National Geode SC1100 ATA33 controller> port
> 0x1f0-0x1f7,0x3f6,0x170-0x177,0x376,0xe000-0xe00f at device 18.2 on pci0
>
> And eventually, after a lot of command timeouts, I will get:
>
> ada0: 16.700MB/s transfers (PIO4, PIO 512bytes)
> ada0: 3825MB (7835184 512 byte sectors: 16H 63S/T 7773C)
> ada0: Previously was known as ad0
>
> However, the system continues issuing failed ATA_IDENTIFY commands after
> this and never succeeds in booting. That ada device being detected there is
> a 4GB CompactFlash card. In order to eliminate the possibility that the
> hardware or card do not support UDMA, write caching, etc, I am booting this
> 10.1-RELEASE-p13 kernel with the following kernel hints in loader.conf:
>
> hint.ata.0.mode="PIO4"
> hint.ata.1.mode="PIO4"
> hint.ahci.0.msi="0"
> hint.atapci.0.msi="0"
> hint.acpi.0.disabled="1"
> kern.cam.ada.write_cache="0"
>
> Removing these hints does not make any difference in the outcome.
>
> It has been a while but I'm no stranger to -hackers or this sort of
> debugging, but I'm wholly unfamiliar with the CAM subsystem. I've compiled
> and booted a 10.1-RELEASE-p13 kernel with all CAM debug flags enabled and
> the complete debug log of a boot attempt can be seen here:
>
> https://gist.github.com/bval/0ab616a57b2846f633ab
>
> Is there a developer more familiar with CAM who can take a look at this and
> advise me on what might be happening or where to go next in debugging this?
> I'm willing to do the legwork just need some guidance.
>

The oldest Soekris 4801 boards that I have indeed do not support UDMA. I 
have always used this in /boot/loader.conf:

hw.ata.ata_dma="0"

to prevent issues like you describe. My systems are now at 10.1-STABLE.

Kind regards,

Hans Ottevanger

Eindhoven, Netherlands
www.beastielabs.net