Sorry, I compiled that custom kernel based on stable instead of current.
I have now compiled a version based on current @ 2014-12-03. I get the
same panic when booting in xhci mode using the kernel based on current
as I did with the kernel based on stable. Same behavior with ehci mode
as well--it boots fine and I can get a dmesg. Here is the dmesg from my
boot to the custom kernel based on *current* using *ehci* mode:

OpenBSD 5.6-current (SCOTT.MP) #1: Wed Dec  3 08:23:40 PST 2014
    root@foo.localdomain:/usr/src/sys/arch/amd64/compile/SCOTT.MP
RTC BIOS diagnostic error 
ff<clock_battery,ROM_cksum,config_unit,memory_size,fixed_disk,invalid_time>
real mem = 8511332352 (8117MB)
avail mem = 8280907776 (7897MB)
mpath0 at root
scsibus0 at mpath0: 256 targets
mainbus0 at root
bios0 at mainbus0: SMBIOS rev. 2.4 @ 0xe0000 (42 entries)
bios0: vendor Apple Inc. version "MBA61.88Z.0099.B16.1408291503" date 08/29/2014
bios0: Apple Inc. MacBookAir6,1
acpi0 at bios0: rev 2
acpi0: sleep states S0 S3 S4 S5
acpi0: tables DSDT FACP HPET APIC SBST ECDT SSDT SSDT SSDT SSDT SSDT SSDT SSDT 
SSDT MCFG DMAR
acpi0: wakeup devices P0P2(S3) EC__(S3) HDEF(S3) RP01(S3) RP02(S3) RP03(S3) 
ARPT(S4) RP05(S3) RP06(S3) SPIT(S3) XHC1(S3) ADP1(S3) LID0(S3)
acpitimer0 at acpi0: 3579545 Hz, 24 bits
acpihpet0 at acpi0: 14318179 Hz
acpimadt0 at acpi0 addr 0xfee00000: PC-AT compat
cpu0 at mainbus0: apid 0 (boot processor)
cpu0: Intel(R) Core(TM) i7-4650U CPU @ 1.70GHz, 1600.27 MHz
cpu0: 
FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CFLUSH,DS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,PBE,SSE3,PCLMUL,DTES64,MWAIT,DS-CPL,VMX,SMX,EST,TM2,SSSE3,FMA3,CX16,xTPR,PDCM,PCID,SSE4.1,SSE4.2,x2APIC,MOVBE,POPCNT,DEADLINE,AES,XSAVE,AVX,F16C,RDRAND,NXE,PAGE1GB,LONG,LAHF,ABM,PERF,ITSC,FSGSBASE,BMI1,HLE,AVX2,SMEP,BMI2,ERMS,INVPCID,RTM
cpu0: 256KB 64b/line 8-way L2 cache
cpu0: smt 0, core 0, package 0
mtrr: Pentium Pro MTRR support, 10 var ranges, 88 fixed ranges
cpu0: apic clock running at 100MHz
cpu1 at mainbus0: apid 2 (application processor)
cpu1: Intel(R) Core(TM) i7-4650U CPU @ 1.70GHz, 1600.01 MHz
cpu1: 
FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CFLUSH,DS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,PBE,SSE3,PCLMUL,DTES64,MWAIT,DS-CPL,VMX,SMX,EST,TM2,SSSE3,FMA3,CX16,xTPR,PDCM,PCID,SSE4.1,SSE4.2,x2APIC,MOVBE,POPCNT,DEADLINE,AES,XSAVE,AVX,F16C,RDRAND,NXE,PAGE1GB,LONG,LAHF,ABM,PERF,ITSC,FSGSBASE,BMI1,HLE,AVX2,SMEP,BMI2,ERMS,INVPCID,RTM
cpu1: 256KB 64b/line 8-way L2 cache
cpu1: smt 0, core 1, package 0
cpu2 at mainbus0: apid 1 (application processor)
cpu2: Intel(R) Core(TM) i7-4650U CPU @ 1.70GHz, 1600.01 MHz
cpu2: 
FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CFLUSH,DS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,PBE,SSE3,PCLMUL,DTES64,MWAIT,DS-CPL,VMX,SMX,EST,TM2,SSSE3,FMA3,CX16,xTPR,PDCM,PCID,SSE4.1,SSE4.2,x2APIC,MOVBE,POPCNT,DEADLINE,AES,XSAVE,AVX,F16C,RDRAND,NXE,PAGE1GB,LONG,LAHF,ABM,PERF,ITSC,FSGSBASE,BMI1,HLE,AVX2,SMEP,BMI2,ERMS,INVPCID,RTM
cpu2: 256KB 64b/line 8-way L2 cache
cpu2: smt 1, core 0, package 0
cpu3 at mainbus0: apid 3 (application processor)
cpu3: Intel(R) Core(TM) i7-4650U CPU @ 1.70GHz, 1600.01 MHz
cpu3: 
FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CFLUSH,DS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,PBE,SSE3,PCLMUL,DTES64,MWAIT,DS-CPL,VMX,SMX,EST,TM2,SSSE3,FMA3,CX16,xTPR,PDCM,PCID,SSE4.1,SSE4.2,x2APIC,MOVBE,POPCNT,DEADLINE,AES,XSAVE,AVX,F16C,RDRAND,NXE,PAGE1GB,LONG,LAHF,ABM,PERF,ITSC,FSGSBASE,BMI1,HLE,AVX2,SMEP,BMI2,ERMS,INVPCID,RTM
cpu3: 256KB 64b/line 8-way L2 cache
cpu3: smt 1, core 1, package 0
ioapic0 at mainbus0: apid 2 pa 0xfec00000, version 20, 40 pins
acpiec0 at acpi0
acpimcfg0 at acpi0 addr 0xe0000000, bus 0-155
acpiprt0 at acpi0: bus 0 (PCI0)
acpiprt1 at acpi0: bus -1 (P0P2)
acpiprt2 at acpi0: bus 1 (RP01)
acpiprt3 at acpi0: bus 2 (RP02)
acpiprt4 at acpi0: bus 3 (RP03)
acpiprt5 at acpi0: bus 5 (RP05)
acpiprt6 at acpi0: bus 4 (RP06)
acpicpu0 at acpi0: C3, C1, PSS
acpicpu1 at acpi0: C3, C1, PSS
acpicpu2 at acpi0: C3, C1, PSS
acpicpu3 at acpi0: C3, C1, PSS
acpibat0 at acpi0: BAT0 model "3545797981023400290" type 3545797981528607052 
oem "3545797981528608836"
acpiac0 at acpi0: AC unit online
acpibtn0 at acpi0: LID0
acpibtn1 at acpi0: PWRB
acpibtn2 at acpi0: SLPB
acpivideo0 at acpi0: IGPU
acpivout0 at acpivideo0: DD01
cpu0: Enhanced SpeedStep 1600 MHz: speeds: 2301, 2300, 2200, 2100, 2000, 1900, 
1800, 1700, 1600, 1500, 1400, 1300, 1200, 1100, 1000, 900, 800, 759 MHz
memory map conflict 0xe00f8000/0x1000
memory map conflict 0xfed1c000/0x4000
memory map conflict 0xffe10000/0x30000
pci0 at mainbus0 bus 0
pchb0 at pci0 dev 0 function 0 "Intel Core 4G Host" rev 0x09
vga1 at pci0 dev 2 function 0 "Intel HD Graphics 5000" rev 0x09
intagp at vga1 not configured
inteldrm0 at vga1
drm0 at inteldrm0
drm: Memory usable by graphics device = 2048M
error: [drm:pid0:i915_write32] *ERROR* Unknown unclaimed register before 
writing to 100000
error: [drm:pid0:intel_dp_set_link_train] *ERROR* Timed out waiting for DP idle 
patterns
error: [drm:pid0:i915_write32] *ERROR* Unknown unclaimed register before 
writing to 64040
inteldrm0: 1366x768
wsdisplay0 at vga1 mux 1: console (std, vt100 emulation)
wsdisplay0: screen 1-5 added (std, vt100 emulation)
azalia0 at pci0 dev 3 function 0 "Intel Core 4G HD Audio" rev 0x09: msi
azalia0: No codecs found
xhci0 at pci0 dev 20 function 0 "Intel 8 Series xHCI" rev 0x04: msi
xhci0: xHCI version 1.0
xhci0: CAPLENGTH=0x80
xhci0: DOORBELL=0x3000
xhci0: RUNTIME=0x2000
xhci0: 32 bytes context
xhci0: supported page size 0x00000001
xhci0: 13 ports and 32 slots
xhci0: 16 scratch pages
xhci0: USB3PRM / USB3.0 configurable ports: 0x0000000f
xhci0: USB3_PSSEN / Enabled USB3.0 ports under xHCI: 0x0000000f
xhci0: XUSB2PRM / USB2.0 ports can switch from EHCI to xHCI:0x000001ff
xhci0: XUSB2PR / USB2.0 ports under xHCI: 0x000001ff
usb0 at xhci0: USB revision 3.0
uhub0 at usb0 "Intel xHCI root hub" rev 3.00/1.00 addr 1
uhub0: 13 ports with 13 removable, self powered
xhci0: DCBAAP=00x8cf7e000
xhci0: CRCR=00 (000000008ccfb000)
xhci0: ERSTBA=00x8ccfafc0
xhci0: ERDP=00x8cf7d000
xhci0: USBCMD=0x5
xhci0: IMAN=0x2
"Intel 8 Series MEI" rev 0x04 at pci0 dev 22 function 0 not configured
azalia1 at pci0 dev 27 function 0 "Intel 8 Series HD Audio" rev 0x04: msi
azalia1: codecs: Cirrus Logic/0x4208
audio0 at azalia1
ppb0 at pci0 dev 28 function 0 "Intel 8 Series PCIE" rev 0xe4
pci1 at ppb0 bus 1
ppb1 at pci0 dev 28 function 1 "Intel 8 Series PCIE" rev 0xe4: msi
pci2 at ppb1 bus 2
vendor "Broadcom", unknown product 0x1570 (class multimedia subclass 
miscellaneous, rev 0x00) at pci2 dev 0 function 0 not configured
ppb2 at pci0 dev 28 function 2 "Intel 8 Series PCIE" rev 0xe4: msi
pci3 at ppb2 bus 3
vendor "Broadcom", unknown product 0x43a0 (class network subclass 
miscellaneous, rev 0x03) at pci3 dev 0 function 0 not configured
ppb3 at pci0 dev 28 function 4 "Intel 8 Series PCIE" rev 0xe4: msi
pci4 at ppb3 bus 5
ppb4 at pci4 dev 0 function 0 vendor "Intel", unknown product 0x1547 rev 0x03
pci5 at ppb4 bus 6
ppb5 at pci5 dev 0 function 0 vendor "Intel", unknown product 0x1547 rev 0x03: 
msi
pci6 at ppb5 bus 7
vendor "Intel", unknown product 0x1547 (class system subclass miscellaneous, 
rev 0x03) at pci6 dev 0 function 0 not configured
ppb6 at pci5 dev 3 function 0 vendor "Intel", unknown product 0x1547 rev 0x03: 
msi
pci7 at ppb6 bus 8
ppb7 at pci5 dev 4 function 0 vendor "Intel", unknown product 0x1547 rev 0x03: 
msi
pci8 at ppb7 bus 57
ppb8 at pci5 dev 5 function 0 vendor "Intel", unknown product 0x1547 rev 0x03: 
msi
pci9 at ppb8 bus 106
ppb9 at pci5 dev 6 function 0 vendor "Intel", unknown product 0x1547 rev 0x03: 
msi
pci10 at ppb9 bus 107
ppb10 at pci0 dev 28 function 5 "Intel 8 Series PCIE" rev 0xe4: msi
pci11 at ppb10 bus 4
ahci0 at pci11 dev 0 function 0 "Samsung S4LN053X01" rev 0x01: msi, AHCI 1.3
scsibus1 at ahci0: 32 targets
sd0 at scsibus1 targ 0 lun 0: <ATA, APPLE SSD SM0512, UXM2> SCSI3 0/direct 
fixed naa.5002538655584d30
sd0: 477102MB, 512 bytes/sector, 977105060 sectors, thin
ehci0 at pci0 dev 29 function 0 "Intel 8 Series USB" rev 0x04: apic 2 int 22
usb1 at ehci0: USB revision 2.0
uhub1 at usb1 "Intel EHCI root hub" rev 2.00/1.00 addr 1
uhub1: 2 ports with 2 removable, self powered
pcib0 at pci0 dev 31 function 0 "Intel 8 Series LPC" rev 0x04
ichiic0 at pci0 dev 31 function 3 "Intel 8 Series SMBus" rev 0x04: apic 2 int 18
iic0 at ichiic0
iic0: addr 0x2c 03=fc 05=6c 06=20 71=06 72=80 86=65 90=38 91=15 92=16 93=3d 
94=6a 95=8c 96=6e 97=84 98=3d 99=02 9a=9f 9f=7c a0=7f a1=b5 a2=bf a3=7b a4=28 
a5=cf a6=64 a7=2d words 00=0000 01=0000 02=00fc 03=fc00 04=006c 05=6c40 06=4000 
07=0000
isa0 at pcib0
isadma0 at isa0
com0 at isa0 port 0x3f8/8 irq 4: ns8250, no fifo
pcppi0 at isa0 port 0x61
spkr0 at pcppi0
uhub1: intr status=0
xhci0: port=1 change=0x02
uhub0: intr status=0
xhci0: port=3 change=0x08
uhub0: intr status=0
xhci0: port=5 change=0x20
uhub0: intr status=0
nvram: invalid checksum
uhub0: port 1 status=0x0101 change=0x0001
xhci0: port=1 change=0x02
uhub0: intr status=0
xhci0: xhci_cmd_slot_control
xhci0: dev 1, input=0xffffff008cf71000 slot=0xffffff008cf71020 
ep0=0xffffff008cf71040
xhci0: dev 1, setting DCBAA to 0x000000008cced000
xhci_pipe_init: pipe=0xffff8000002ed000 addr=0 depth=1 port=1 speed=3 dev 1 dci 
1 (epAddr=0x0)
xhci0: xhci_cmd_set_address BSR=1
xhci0: xhci_cmd_set_address BSR=0
xhci0: dev 1 addr 1
umass0 at uhub0 port 1 configuration 1 interface 0 "Corsair Voyager GT" rev 
2.00/11.00 addr 2
umass0: using SCSI over Bulk-Only
xhci_pipe_init: pipe=0xffff8000002ef000 addr=2 depth=1 port=1 speed=3 dev 1 dci 
4 (epAddr=0x2)
xhci0: xhci_cmd_configure_ep dev 1
xhci_pipe_init: pipe=0xffff8000002f0000 addr=2 depth=1 port=1 speed=3 dev 1 dci 
3 (epAddr=0x81)
xhci0: xhci_cmd_configure_ep dev 1
scsibus2 at umass0: 2 targets, initiator 0
sd1 at scsibus2 targ 1 lun 0: <Corsair, VoyagerGT, 1100> SCSI0 0/direct 
removable serial.1b1c1a90000000000309
sd1: 7904MB, 512 bytes/sector, 16187392 sectors
uhub0: port 2 status=0x0900 change=0x0000
uhub0: port 3 status=0x0101 change=0x0001
xhci0: port=3 change=0x08
uhub0: intr status=0
xhci0: xhci_cmd_slot_control
xhci0: dev 2, input=0xffffff008cceb000 slot=0xffffff008cceb020 
ep0=0xffffff008cceb040
xhci0: dev 2, setting DCBAA to 0x000000008cf6e000
xhci_pipe_init: pipe=0xffff8000002f2000 addr=0 depth=1 port=3 speed=2 dev 2 dci 
1 (epAddr=0x0)
xhci0: xhci_cmd_set_address BSR=1
xhci0: xhci_cmd_set_address BSR=0
xhci0: dev 2 addr 2
uhub2 at uhub0 port 3 "Apple Inc. BRCM20702 Hub" rev 2.00/1.00 addr 3
uhub2: 3 ports with 0 removable, self powered
xhci_pipe_init: pipe=0xffff8000002f3000 addr=3 depth=1 port=3 speed=2 dev 2 dci 
3 (epAddr=0x81)
xhci0: xhci_cmd_configure_ep dev 2
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: port 1 status=0x0101 change=0x0001
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
xhci0: xhci_cmd_slot_control
uhub2: intr status=0
xhci0: dev 3, input=0xffffff008cce9000 slot=0xffffff008cce9020 
ep0=0xffffff008cce9040
uhub2: intr status=0
xhci0: dev 3, setting DCBAA to 0x000000008cf6c000
uhub2: intr status=0
xhci_pipe_init: pipe=0xffff8000002f4000 addr=0 depth=2 port=1 speed=2 dev 3 dci 
1 (epAddr=0x0)
uhub2: intr status=0
xhci0: xhci_cmd_set_address BSR=1
uhub2: intr status=0
xhci0: xhci_cmd_set_address BSR=0
uhub2: intr status=0
xhci0: dev 3 addr 3
uhub2: intr status=0
uhub2: intr status=0
uhidev0 at uhub2uhub2: intr status=0
 port 1 configuration 1uhub2: intr status=0
 interface 0 "Apple Computer product 0x820a" rev 2.00/1.00 addr 4
uhub2: intr status=0
uhub2: intr status=0
uhidev0: iclass 3/1uhub2: intr status=0
, 1 report iduhub2: intr status=0

uhub2: intr status=0
ukbd0 at uhidev0uhub2: intr status=0
 reportid 1uhub2: intr status=0
: 8 variable keys, 6 key codesuhub2: intr status=0

uhub2: intr status=0
xhci_pipe_init: pipe=0xffff8000002f5000 addr=4 depth=2 port=1 speed=2 dev 3 dci 
3 (epAddr=0x81)
uhub2: intr status=0
xhci0: xhci_cmd_configure_ep dev 3
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
wskbd0 at ukbd0uhub2: intr status=0
: console keyboarduhub2: intr status=0
, using wsdisplay0uhub2: intr status=0

uhub2: intr status=0
uhub2: port 2 status=0x0101 change=0x0001
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
xhci0: xhci_cmd_slot_control
uhub2: intr status=0
xhci0: dev 4, input=0xffffff008cce7000 slot=0xffffff008cce7020 
ep0=0xffffff008cce7040
uhub2: intr status=0
xhci0: dev 4, setting DCBAA to 0x000000008cf6a000
uhub2: intr status=0
xhci_pipe_init: pipe=0xffff8000002f7000 addr=0 depth=2 port=2 speed=2 dev 4 dci 
1 (epAddr=0x0)
uhub2: intr status=0
xhci0: xhci_cmd_set_address BSR=1
uhub2: intr status=0
xhci0: xhci_cmd_set_address BSR=0
uhub2: intr status=0
xhci0: dev 4 addr 4
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhidev1 at uhub2uhub2: intr status=0
 port 2uhub2: intr status=0
 configuration 1uhub2: intr status=0
 interface 0uhub2: intr status=0
 "Apple Computer product 0x820b" rev 2.00/1.00 addr 5
uhub2: intr status=0
uhidev1: iclass 3/1uhub2: intr status=0
, 2 report idsuhub2: intr status=0

uhub2: intr status=0
ums0 at uhidev1uhub2: intr status=0
 reportid 2uhub2: intr status=0
: 3 buttonsuhub2: intr status=0

uhub2: intr status=0
wsmouse0 at ums0uhub2: intr status=0
 mux 0
uhub2: intr status=0
uhub2: port 3 status=0x0101 change=0x0001
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
uhub2: intr status=0
xhci0: xhci_cmd_slot_control
xhci0: dev 5, input=0xffffff008cf69000 slot=0xffffff008cf69020 
ep0=0xffffff008cf69040
xhci0: dev 5, setting DCBAA to 0x000000008cce5000
xhci_pipe_init: pipe=0xffff8000002f8000 addr=0 depth=2 port=3 speed=2 dev 5 dci 
1 (epAddr=0x0)
xhci0: xhci_cmd_set_address BSR=1
xhci0: xhci_cmd_set_address BSR=0
xhci0: dev 5 addr 5
ugen0 at uhub2 port 3 "Apple Inc. Bluetooth USB Host Controller" rev 2.00/0.99 
addr 6
uhub0: port 4 status=0x0900 change=0x0000
uhub0: port 5 status=0x0101 change=0x0001
xhci0: port=5 change=0x20
uhub0: intr status=0
xhci0: xhci_cmd_slot_control
xhci0: dev 6, input=0xffffff008cf67000 slot=0xffffff008cf67020 
ep0=0xffffff008cf67040
xhci0: dev 6, setting DCBAA to 0x000000008cce3000
xhci_pipe_init: pipe=0xffff8000002ff000 addr=0 depth=1 port=5 speed=2 dev 6 dci 
1 (epAddr=0x0)
xhci0: xhci_cmd_set_address BSR=1
xhci0: xhci_cmd_set_address BSR=0
xhci0: dev 6 addr 6
uhidev2 at uhub0 port 5 configuration 1 interface 0 "Apple Inc. Apple Internal 
Keyboard / Trackpad" rev 2.00/1.71 addr 7
xhci0: xhci_cmd_reset_endpoint_async dev 6 dci 1
xhci0: xhci_cmd_set_tr_deq_async dev 6 dci 1
uhidev2: iclass 3/0, 63 report ids
uhid0 at uhidev2 reportid 63: input=64, output=0, feature=0
uhidev3 at uhub0 port 5 configuration 1 interface 1 "Apple Inc. Apple Internal 
Keyboard / Trackpad" rev 2.00/1.71 addr 7
uhidev3: iclass 3/1, 63 report ids
ukbd1 at uhidev3 reportid 1: 8 variable keys, 6 key codes, country code 33
wskbd1 at ukbd1 mux 1
xhci_pipe_init: pipe=0xffff800000301000 addr=7 depth=1 port=5 speed=2 dev 6 dci 
5 (epAddr=0x82)
xhci0: xhci_cmd_configure_ep dev 6
wskbd1: connecting to wsdisplay0
uhid1 at uhidev3 reportid 9: input=0, output=0, feature=3
uhid2 at uhidev3 reportid 63: input=64, output=0, feature=0
ubcmtp0 at uhub0 port 5 configuration 1 interface 2 "Apple Inc. Apple Internal 
Keyboard / Trackpad" rev 2.00/1.71 addr 7
wsmouse1 at ubcmtp0 mux 0
uhub0: port 6 status=0x0900 change=0x0000
uhub0: port 7 status=0x0900 change=0x0000
uhub0: port 8 status=0x0900 change=0x0000
uhub0: port 9 status=0x0900 change=0x0000
uhub0: port 10 status=0x0900 change=0x0000
uhub0: port 11 status=0x0900 change=0x0000
uhub0: port 12 status=0x0900 change=0x0000
uhub0: port 13 status=0x0900 change=0x0000
uhub1: port 1 status=0x0501 change=0x0001
uhub3 at uhub1 port 1 "Intel Rate Matching Hub" rev 2.00/0.04 addr 2
uhub3: 8 ports with 8 removable, self powered, single transaction translator
uhub3: port 1 status=0x0100 change=0x0000
uhub3: port 2 status=0x0100 change=0x0000
uhub3: port 3 status=0x0100 change=0x0000
uhub3: port 4 status=0x0100 change=0x0000
uhub3: port 5 status=0x0100 change=0x0000
uhub3: port 6 status=0x0100 change=0x0000
uhub3: port 7 status=0x0100 change=0x0000
uhub3: port 8 status=0x0100 change=0x0000
uhub1: port 2 status=0x0500 change=0x0000
vscsi0 at root
scsibus3 at vscsi0: 256 targets
softraid0 at root
scsibus4 at softraid0: 256 targets
root on sd1a (4c16713a536188bf.a) swap on sd1b dump on sd1b
clock: unknown CMOS layout

Excerpts from Scott Bonds's message of 2014-12-02 17:39:58 -0800:
> I compiled a custom kernel with the options you specified. When I do a
> normal boot (xhci mode) using the custom kernel, instead of a hang I get
> a panic. The last lines on the screen before the panic instructions are:
> 
> scscibus3 at softraid0: 256 targets
> panic: root device (4c16713a536188bf) not found
> stopped at      Debugger+0x9:   leave
> 
> The keyboard does not respond after the panic.
> 
> Booting the custom kernel after putting the laptop into ehci mode I'm
> able to boot successfully and get a dmesg, though perhaps not the one
> you need, since its no longer in xhci mode. :( Here it is:
> 
> OpenBSD 5.6-stable (SCOTT.MP) #0: Tue Dec  2 16:55:45 PST 2014
>     root@foo.localdomain:/usr/src/sys/arch/amd64/compile/SCOTT.MP
> RTC BIOS diagnostic error 
> ff<clock_battery,ROM_cksum,config_unit,memory_size,fixed_disk,invalid_time>
> real mem = 8511332352 (8117MB)
> avail mem = 8275972096 (7892MB)
> mpath0 at root
> scsibus0 at mpath0: 256 targets
> mainbus0 at root
> bios0 at mainbus0: SMBIOS rev. 2.4 @ 0xe0000 (42 entries)
> bios0: vendor Apple Inc. version "MBA61.88Z.0099.B16.1408291503" date 
> 08/29/2014
> bios0: Apple Inc. MacBookAir6,1
> acpi0 at bios0: rev 2
> acpi0: sleep states S0 S3 S4 S5
> acpi0: tables DSDT FACP HPET APIC SBST ECDT SSDT SSDT SSDT SSDT SSDT SSDT 
> SSDT SSDT MCFG DMAR
> acpi0: wakeup devices P0P2(S3) EC__(S3) HDEF(S3) RP01(S3) RP02(S3) RP03(S3) 
> ARPT(S4) RP05(S3) RP06(S3) SPIT(S3) XHC1(S3) ADP1(S3) LID0(S3)
> acpitimer0 at acpi0: 3579545 Hz, 24 bits
> acpihpet0 at acpi0: 14318179 Hz
> acpimadt0 at acpi0 addr 0xfee00000: PC-AT compat
> cpu0 at mainbus0: apid 0 (boot processor)
> cpu0: Intel(R) Core(TM) i7-4650U CPU @ 1.70GHz, 1600.21 MHz
> cpu0: 
> FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CFLUSH,DS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,PBE,SSE3,PCLMUL,DTES64,MWAIT,DS-CPL,VMX,SMX,EST,TM2,SSSE3,FMA3,CX16,xTPR,PDCM,PCID,SSE4.1,SSE4.2,x2APIC,MOVBE,POPCNT,DEADLINE,AES,XSAVE,AVX,F16C,RDRAND,NXE,PAGE1GB,LONG,LAHF,ABM,PERF,ITSC,FSGSBASE,BMI1,HLE,AVX2,SMEP,BMI2,ERMS,INVPCID,RTM
> cpu0: 256KB 64b/line 8-way L2 cache
> cpu0: smt 0, core 0, package 0
> mtrr: Pentium Pro MTRR support, 10 var ranges, 88 fixed ranges
> cpu0: apic clock running at 100MHz
> cpu0: mwait min=64, max=64, C-substates=0.2.1.2.4, IBE
> cpu1 at mainbus0: apid 2 (application processor)
> cpu1: Intel(R) Core(TM) i7-4650U CPU @ 1.70GHz, 1600.01 MHz
> cpu1: 
> FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CFLUSH,DS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,PBE,SSE3,PCLMUL,DTES64,MWAIT,DS-CPL,VMX,SMX,EST,TM2,SSSE3,FMA3,CX16,xTPR,PDCM,PCID,SSE4.1,SSE4.2,x2APIC,MOVBE,POPCNT,DEADLINE,AES,XSAVE,AVX,F16C,RDRAND,NXE,PAGE1GB,LONG,LAHF,ABM,PERF,ITSC,FSGSBASE,BMI1,HLE,AVX2,SMEP,BMI2,ERMS,INVPCID,RTM
> cpu1: 256KB 64b/line 8-way L2 cache
> cpu1: smt 0, core 1, package 0
> cpu2 at mainbus0: apid 1 (application processor)
> cpu2: Intel(R) Core(TM) i7-4650U CPU @ 1.70GHz, 1600.01 MHz
> cpu2: 
> FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CFLUSH,DS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,PBE,SSE3,PCLMUL,DTES64,MWAIT,DS-CPL,VMX,SMX,EST,TM2,SSSE3,FMA3,CX16,xTPR,PDCM,PCID,SSE4.1,SSE4.2,x2APIC,MOVBE,POPCNT,DEADLINE,AES,XSAVE,AVX,F16C,RDRAND,NXE,PAGE1GB,LONG,LAHF,ABM,PERF,ITSC,FSGSBASE,BMI1,HLE,AVX2,SMEP,BMI2,ERMS,INVPCID,RTM
> cpu2: 256KB 64b/line 8-way L2 cache
> cpu2: smt 1, core 0, package 0
> cpu3 at mainbus0: apid 3 (application processor)
> cpu3: Intel(R) Core(TM) i7-4650U CPU @ 1.70GHz, 1600.01 MHz
> cpu3: 
> FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CFLUSH,DS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,PBE,SSE3,PCLMUL,DTES64,MWAIT,DS-CPL,VMX,SMX,EST,TM2,SSSE3,FMA3,CX16,xTPR,PDCM,PCID,SSE4.1,SSE4.2,x2APIC,MOVBE,POPCNT,DEADLINE,AES,XSAVE,AVX,F16C,RDRAND,NXE,PAGE1GB,LONG,LAHF,ABM,PERF,ITSC,FSGSBASE,BMI1,HLE,AVX2,SMEP,BMI2,ERMS,INVPCID,RTM
> cpu3: 256KB 64b/line 8-way L2 cache
> cpu3: smt 1, core 1, package 0
> ioapic0 at mainbus0: apid 2 pa 0xfec00000, version 20, 40 pins
> acpiec0 at acpi0
> acpimcfg0 at acpi0 addr 0xe0000000, bus 0-155
> acpiprt0 at acpi0: bus 0 (PCI0)
> acpiprt1 at acpi0: bus -1 (P0P2)
> acpiprt2 at acpi0: bus 1 (RP01)
> acpiprt3 at acpi0: bus 2 (RP02)
> acpiprt4 at acpi0: bus 3 (RP03)
> acpiprt5 at acpi0: bus 5 (RP05)
> acpiprt6 at acpi0: bus 4 (RP06)
> acpicpu0 at acpi0: C3, C1, PSS
> acpicpu1 at acpi0: C3, C1, PSS
> acpicpu2 at acpi0: C3, C1, PSS
> acpicpu3 at acpi0: C3, C1, PSS
> acpibat0 at acpi0: BAT0 model "3545797981023400290" type 3545797981528607052 
> oem "3545797981528608836"
> acpiac0 at acpi0: AC unit online
> acpibtn0 at acpi0: LID0
> acpibtn1 at acpi0: PWRB
> acpibtn2 at acpi0: SLPB
> acpivideo0 at acpi0: IGPU
> acpivout0 at acpivideo0: DD01
> cpu0: Enhanced SpeedStep 1600 MHz: speeds: 2301, 2300, 2200, 2100, 2000, 
> 1900, 1800, 1700, 1600, 1500, 1400, 1300, 1200, 1100, 1000, 900, 800, 759 MHz
> memory map conflict 0xe00f8000/0x1000
> memory map conflict 0xfed1c000/0x4000
> memory map conflict 0xffe10000/0x30000
> pci0 at mainbus0 bus 0
> pchb0 at pci0 dev 0 function 0 "Intel Core 4G Host" rev 0x09
> vga1 at pci0 dev 2 function 0 "Intel HD Graphics 5000" rev 0x09
> intagp at vga1 not configured
> inteldrm0 at vga1
> drm0 at inteldrm0
> drm: Memory usable by graphics device = 2048M
> error: [drm:pid0:i915_write32] *ERROR* Unknown unclaimed register before 
> writing to 100000
> error: [drm:pid0:intel_dp_set_link_train] *ERROR* Timed out waiting for DP 
> idle patterns
> error: [drm:pid0:i915_write32] *ERROR* Unknown unclaimed register before 
> writing to 64040
> inteldrm0: 1366x768
> wsdisplay0 at vga1 mux 1: console (std, vt100 emulation)
> wsdisplay0: screen 1-5 added (std, vt100 emulation)
> azalia0 at pci0 dev 3 function 0 "Intel Core 4G HD Audio" rev 0x09: msi
> azalia0: No codecs found
> "Intel 8 Series xHCI" rev 0x04 at pci0 dev 20 function 0 not configured
> "Intel 8 Series MEI" rev 0x04 at pci0 dev 22 function 0 not configured
> azalia1 at pci0 dev 27 function 0 "Intel 8 Series HD Audio" rev 0x04: msi
> azalia1: codecs: Cirrus Logic/0x4208
> audio0 at azalia1
> ppb0 at pci0 dev 28 function 0 "Intel 8 Series PCIE" rev 0xe4
> pci1 at ppb0 bus 1
> ppb1 at pci0 dev 28 function 1 "Intel 8 Series PCIE" rev 0xe4: msi
> pci2 at ppb1 bus 2
> vendor "Broadcom", unknown product 0x1570 (class multimedia subclass 
> miscellaneous, rev 0x00) at pci2 dev 0 function 0 not configured
> ppb2 at pci0 dev 28 function 2 "Intel 8 Series PCIE" rev 0xe4: msi
> pci3 at ppb2 bus 3
> vendor "Broadcom", unknown product 0x43a0 (class network subclass 
> miscellaneous, rev 0x03) at pci3 dev 0 function 0 not configured
> ppb3 at pci0 dev 28 function 4 "Intel 8 Series PCIE" rev 0xe4: msi
> pci4 at ppb3 bus 5
> ppb4 at pci4 dev 0 function 0 vendor "Intel", unknown product 0x1547 rev 0x03
> pci5 at ppb4 bus 6
> ppb5 at pci5 dev 0 function 0 vendor "Intel", unknown product 0x1547 rev 
> 0x03: msi
> pci6 at ppb5 bus 7
> vendor "Intel", unknown product 0x1547 (class system subclass miscellaneous, 
> rev 0x03) at pci6 dev 0 function 0 not configured
> ppb6 at pci5 dev 3 function 0 vendor "Intel", unknown product 0x1547 rev 
> 0x03: msi
> pci7 at ppb6 bus 8
> ppb7 at pci5 dev 4 function 0 vendor "Intel", unknown product 0x1547 rev 
> 0x03: msi
> pci8 at ppb7 bus 57
> ppb8 at pci5 dev 5 function 0 vendor "Intel", unknown product 0x1547 rev 
> 0x03: msi
> pci9 at ppb8 bus 106
> ppb9 at pci5 dev 6 function 0 vendor "Intel", unknown product 0x1547 rev 
> 0x03: msi
> pci10 at ppb9 bus 107
> ppb10 at pci0 dev 28 function 5 "Intel 8 Series PCIE" rev 0xe4: msi
> pci11 at ppb10 bus 4
> ahci0 at pci11 dev 0 function 0 vendor "Samsung", unknown product 0x1600 rev 
> 0x01: msi, AHCI 1.3
> scsibus1 at ahci0: 32 targets
> sd0 at scsibus1 targ 0 lun 0: <ATA, APPLE SSD SM0512, UXM2> SCSI3 0/direct 
> fixed naa.5002538655584d30
> sd0: 477102MB, 512 bytes/sector, 977105060 sectors, thin
> ehci0 at pci0 dev 29 function 0 "Intel 8 Series USB" rev 0x04: apic 2 int 22
> usb0 at ehci0: USB revision 2.0
> uhub0 at usb0 "Intel EHCI root hub" rev 2.00/1.00 addr 1
> uhub0: 2 ports with 2 removable, self powered
> pcib0 at pci0 dev 31 function 0 "Intel 8 Series LPC" rev 0x04
> ichiic0 at pci0 dev 31 function 3 "Intel 8 Series SMBus" rev 0x04: apic 2 int 
> 18
> iic0 at ichiic0
> iic0: addr 0x2c 03=fc 05=6b 06=a0 71=06 72=80 86=65 90=38 91=15 92=16 93=3d 
> 94=6a 95=8c 96=6e 97=84 98=3d 99=02 9a=9f 9f=7c a0=7f a1=b5 a2=bf a3=7b a4=28 
> a5=cf a6=64 a7=2d words 00=0000 01=0000 02=00fc 03=fc00 04=006b 05=6ba0 
> 06=a000 07=0000
> isa0 at pcib0
> isadma0 at isa0
> com0 at isa0 port 0x3f8/8 irq 4: ns8250, no fifo
> pcppi0 at isa0 port 0x61
> spkr0 at pcppi0
> uhub0: intr status=0
> nvram: invalid checksum
> uhub0: port 1 status=0x0501 change=0x0001
> uhub1 at uhub0 port 1 "Intel Rate Matching Hub" rev 2.00/0.04 addr 2
> uhub1: 8 ports with 8 removable, self powered, single transaction translator
> uhub1: port 1 status=0x0101 change=0x0001
> uhub1: intr status=0
> uhub1: intr status=0
> uhub1: intr status=0
> uhub1: intr status=0
> uhub1: intr status=0
> uhub1: intr status=0
> umass0 at uhub1 port 1 configuration 1 interface 0 "Corsair Voyager GT" rev 
> 2.00/11.00 addr 3
> umass0: using SCSI over Bulk-Only
> scsibus2 at umass0: 2 targets, initiator 0
> sd1 at scsibus2 targ 1 lun 0: <Corsair, VoyagerGT, 1100> SCSI0 0/direct 
> removable serial.1b1c1a90000000000309
> sd1: 7904MB, 512 bytes/sector, 16187392 sectors
> uhub1: port 2 status=0x0100 change=0x0000
> uhub1: port 3 status=0x0101 change=0x0001
> uhub1: intr status=0
> uhub1: intr status=0
> uhub1: intr status=0
> uhub1: intr status=0
> uhub1: intr status=0
> uhub2 at uhub1 port 3 "Apple Inc. BRCM20702 Hub" rev 2.00/1.00 addr 4
> uhub1: intr status=0
> uhub2: 3 ports with 0 removable, self powered
> uhub1: intr status=0
> uhub1: intr status=0
> uhub2: intr status=0
> uhub2: port 1 status=0x0101 change=0x0001
> uhub1: intr status=0
> uhub2: intr status=0
> uhub1: intr status=0
> uhub2: intr status=0
> uhub1: intr status=0
> uhub2: intr status=0
> uhub1: intr status=0
> uhub2: intr status=0
> uhub1: intr status=0
> uhub2: intr status=0
> uhidev0 at uhub2 port 1 configuration 1uhub1: intr status=0
>  interface 0 "Apple Computer product 0x820a" rev 2.00/1.00 addr 5
> uhidev0: iclass 3/1, 1 report id
> uhub2: intr status=0
> ukbd0 at uhidev0 reportid 1: 8 variable keys, 6 key codes
> uhub1: intr status=0
> uhub2: intr status=0
> uhub1: intr status=0
> uhub2: intr status=0
> uhub1: intr status=0
> uhub2: intr status=0
> wskbd0 at ukbd0: console keyboard, using wsdisplay0
> uhub2: port 2 status=0x0101 change=0x0001
> uhub1: intr status=0
> uhub2: intr status=0
> uhub1: intr status=0
> uhub2: intr status=0
> uhub1: intr status=0
> uhub2: intr status=0
> uhub1: intr status=0
> uhub2: intr status=0
> uhub1: intr status=0
> uhub2: intr status=0
> uhidev1 at uhub2 port 2 configuration 1 interface 0 "Apple Computer product 
> 0x820b" rev 2.00/1.00 addr 6
> uhidev1: iclass 3/1, 2 report ids
> uhub1: intr status=0
> ums0 at uhidev1 reportid 2: 3 buttons
> wsmouse0 at ums0 mux 0
> uhub2: port 3 status=0x0101 change=0x0001
> uhub2: intr status=0
> uhub1: intr status=0
> uhub1: intr status=0
> uhub1: intr status=0
> uhub1: intr status=0
> uhub1: intr status=0
> ugen0 at uhub2 port 3 "Apple Inc. Bluetooth USB Host Controller" rev 
> 2.00/0.99 addr 7
> uhub1: port 4 status=0x0100 change=0x0000
> uhub1: port 5 status=0x0101 change=0x0001
> uhidev2 at uhub1 port 5 configuration 1 interface 0 "Apple Inc. Apple 
> Internal Keyboard / Trackpad" rev 2.00/1.71 addr 8
> uhidev2: iclass 3/0, 63 report ids
> uhid0 at uhidev2 reportid 63: input=64, output=0, feature=0
> uhidev3 at uhub1 port 5 configuration 1 interface 1 "Apple Inc. Apple 
> Internal Keyboard / Trackpad" rev 2.00/1.71 addr 8
> uhidev3: iclass 3/1, 63 report ids
> ukbd1 at uhidev3 reportid 1: 8 variable keys, 6 key codes, country code 33
> wskbd1 at ukbd1 mux 1
> wskbd1: connecting to wsdisplay0
> uhid1 at uhidev3 reportid 9: input=0, output=0, feature=3
> uhid2 at uhidev3 reportid 63: input=64, output=0, feature=0
> ubcmtp0 at uhub1 port 5 configuration 1 interface 2 "Apple Inc. Apple 
> Internal Keyboard / Trackpad" rev 2.00/1.71 addr 8
> wsmouse1 at ubcmtp0 mux 0
> uhub1: port 6 status=0x0100 change=0x0000
> uhub1: port 7 status=0x0100 change=0x0000
> uhub1: port 8 status=0x0100 change=0x0000
> uhub0: port 2 status=0x0500 change=0x0000
> vscsi0 at root
> scsibus3 at vscsi0: 256 targets
> softraid0 at root
> scsibus4 at softraid0: 256 targets
> root on sd1a (4c16713a536188bf.a) swap on sd1b dump on sd1b
> clock: unknown CMOS layout
> 
> Excerpts from Martin Pieuchot's message of 2014-12-02 01:21:07 -0800:
> > On 01/12/14(Mon) 15:41, Scott Bonds wrote:
> > > While investigating the slow hard drive on my MacbookAir6,1, I decided
> > > to take a working installation of -current (20141201 snapshot) on a USB
> > > drive and try booting it on the MBA6,1. I discovered that booting off of
> > > a usb drive (with a full install, i.e. bsd.mp NOT bsd.rd) hangs once the
> > > boot reaches this line:
> > > 
> > > uhub0 at usb0 "Intel xHCI root hub" rev 3.00/1.00 addr 1
> > > 
> > > This behavior manifests while using a 'normal' boot--I did not use the
> > > OSX bless utility to get the builtin USB controller into ehci mode
> > > instead of xhci mode. When I *do* do that (use bless to set the usb
> > > controller into ehci mode) the boot progresses to:
> > > 
> > > scsibus4 at softraid0: 256 targets
> > > 
> > > then pauses there for 5 minutes, then proceeds to boot just fine. When
> > > booting this way, I observe the same pauses/slowness when operating on
> > > the builtin hard drive as mentioned in the thread I started on that
> > > topic:
> > > 
> > > http://marc.info/?l=openbsd-misc&m=141747241629431&w=2
> > > 
> > > Anyway, I mention the xhci boot hang behaviour because I know xhci
> > > development is active, and I thought this result may be
> > > interesting/useful for that.
> > 
> > Such long hang generally means that timeouts are occurring.  If you
> > can compile a kernel with XHCI_DEBUG and UHUB_DEBUG defined and send
> > me a dmesg, it will be much appreciated.
> > 
> > Martin

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