I have more information, hopefully useful, about this problem. To recap,
the installer bsd.rd fails to boot unless I 'disable athn' in UKC. The
installer bsd boots, but of course panics because there is no rootfs. I
managed to install OpenBSD using bsd.rd (with athn disabled), but upon booting
into OpenBSD, I get a fault with a nice trace:
======== BEGIN ========
athn0 at pci2 dev 0 function 0 "Atheros AR9300" rev 0x01: apic 4 int 17
uvm_fault(0xffffffff80d2a0a0, 0x0, 0, 1) -> e
kernel: page fault trap, code=0
Stopped at athn_write_serdes+0x15: movl 0(%r13,%rbx,4),%edx
athn_write_serdes() at athn_write_serdes+0x15
athn_config_pcie() at athn_config_pcie+0x16
ar9003_attach() at ar9003_attach+0x199
athn_attach() at athn_attach+0x586
athn_pci_attach() at athn_pci_attach+0x1de
config_attach() at config_attach+0x1d4
pci_probe_device() at pci_probe_device+0x462
pci_enumerate_bus() at pci_enumerate_bus+0xe9
config_attach() at config_attach+0x1d4
ppbattach() at ppbattach+0x32f
end trace frame: 0xffffffff80e30bf0, count: 0
ddb{0}>
======== END ========
Like the installer bsd.rd, the installed OpenBSD can boot by disabling athn
in UKC. Running 'ps' in ddb shows only 'swapper' running, nothing else.
Hopefully someone will be able to gather something from this trace.
