I think one problem was that in 2.6.38 the kernel saw HEST/GHES was
supported and just tried to communicate with it. Unfortunately the kernel
forgot to tell the BIOS that it supports firmware first mode, so in this
case the firmware is probably blocking the GHES access and the kernel is
confused why.
The following commits resolved that issue (which may not entirely fix the
problem, but might move it along).
9fb0bfe ACPI, APEI, Add WHEA _OSC support
b3b46d7 APEI: Fix WHEA _OSC call
The second one in particular was noticed by Dell. Though I recall that we
needed to update the firmware to get Dell boxes working, but that was
probably for EINJ.
Cheers,
Don