SMP, the aac driver and command timeouts

[Sheldon Hearn]

Hi there,

I've just installed a fresh 4.8-RELEASE on a dual-Xeon (2.6GHz) with 4GB
of RAM.

I'm using the aac driver to support an Adaptec 2120S:

aac0: <Adaptec SCSI RAID 2120S> mem 0xd0000000-0xd3ffffff irq 2 at
      device 2.0 on pci4
aac0: i960RX 100MHz, 48MB cache memory, optional battery present
aac0: Kernel 4.0-0, Build 6003, S/N b7e76e

When I try to boot an SMP kernel (with or without HTT enabled in the
BIOS and kernel), the system fails to boot.

On serial console, I see messages that look like this:

aac0 ... COMMAND 0x...... TIMEOUT AFTER ... seconds

I've googled around, and the advice I've seen is:

1) Make sure your drives have enough power, and
2) Flash up the firmware of your drives.

I'll get the guys at our colo to flash the drive firmware and confirm
that the PSU is a 350W, but I'm under serious time pressure and wanted
to ask in advance whether this is likely to solve my problem, or whether
there are other likely candidates I should investigate.

On the plus side, this box as a FreeBSD installation is faring much
better than it did as a Windows 2000 Advanced Server.  I couldn't even
get Apache2 to start up more than 200 threads.  Try downgrading Windows
2000 from multiprocessor to uniprocessor over serial console. ;-)

TIA,
Sheldon.