Hi Jeff,

I recently built a 2.6.39 kernel (from kernel.org) in order to take
advantage of the ASUS U3S6 adapter card's USB 3.0 capability. The
card's SATA capability had been working nicely (via the AHCI driver)
with the stock openSUSE 11.1 kernel (2.6.27.7-9-default), but that
kernel doesn't have the XHCI driver for USB3.

With the 2.6.39 kernel, the situation is reversed: the card's USB3
works, but SATA doesn't. In particular, the booting process reports
"failed to IDENTIFY (I/O error, err_mask=0x4)" for disks attached to
that adapter, even after trying lower link speeds.

With both kernels, the AHCI driver attached to the SATA adapter by
default, as its PCI ID (1b4b:9120) isn't in any of the tables in
"/lib/modules/2.6.x.y/modules.*".

Since the kernel is Open Source, I looked in the ahci.c files for
both 2.3.39 and 2.6.27.7-9-default, hoping to discover some obvious
difference that would explain the failure. Instead I discovered that
the ahci.c for 2.6.27.7-9-default is about twice as big as ahci.c for
2.6.39. Even though part of that difference is explained by the the
fact that 2.6.27.7-9-default doesn't have an ahci.h file, the diff
was far too extensive to pursue. (I get plenty of that -- debugging
code I didn't write -- at work.)

By the way, kernel 2.6.35.12 also fails in this manner, so it isn't
a recent regression.

For your perusal I have attached to this email the ahci.c from
openSUSE's 2.6.27.7-9-default kernel, along with the boot.msg
showing how 2.6.39 fails (search for "failed to IDENTIFY").

Thanks for your attention, and I hope that a quick solution can be
found.

Paul Kosinski

P.S. As an amusing side note, since the U3S6 card uses a Marvell
chip, I also looked at sata_mv.c. To my amazement, it said it was
originally written by Brett Russ, with whom I had worked closely
about 2 years ago -- i.e., after he did sata_mv -- at my company
(Tervela Inc.).