Steps to reproduce:
1. Plug in USB-to-serial cable.
2. In terminal, do: sudo cu -l /dev/cuaU0 -s 38400
3. Switch to console.
4. Unplug the cable from USB port...
And you get ddb prompt:
kernel: protection fault trap, code=0
Stopped at usb_transfer_complete+0x59: movzbl 0x460
(%rax),% r13d
ddb {0}> trace
usb_transfer_complete() at usb_transfer_complete+0x59
uhci_softintr () at uhci_softintr+0x3f
softintr_dispatch() at softintr_dispatch+0x7f
Xsoftnet() at Xsoftnet+0x2d
--- interrupt ---
end trace frame: 0x0, count: -4
Hardware: Lenovo ThinkPad x61s.
OpenBSD 5.7 (GENERIC.MP) #881: Sun Mar 8 11:04:17 MDT 2015
[email protected]:/usr/src/sys/arch/amd64/compile/GENERIC.MP
real mem = 4201316352 (4006MB)
avail mem = 4085559296 (3896MB)
mpath0 at root
scsibus0 at mpath0: 256 targets
mainbus0 at root
bios0 at mainbus0: SMBIOS rev. 2.4 @ 0xe0010 (63 entries)
bios0: vendor LENOVO version "7NET21WW (1.02 )" date 04/23/2007
bios0: LENOVO 766927G
acpi0 at bios0: rev 2
acpi0: sleep states S0 S3 S4 S5
acpi0: tables DSDT FACP SSDT ECDT TCPA APIC MCFG HPET SLIC BOOT ASF! SSDT
SSDT SSDT SSDT SSDT
acpi0: wakeup devices LID_(S3) SLPB(S3) DURT(S3) IGBE(S4) EXP0(S4) EXP1(S4)
EXP2(S4) EXP3(S4) EXP4(S4) PCI1(S4) USB0(S3) USB1(S3) USB2(S3) USB3(S3)
USB4(S3) EHC0(S3) [...]
acpitimer0 at acpi0: 3579545 Hz, 24 bits
acpiec0 at acpi0
acpimadt0 at acpi0 addr 0xfee00000: PC-AT compat
cpu0 at mainbus0: apid 0 (boot processor)
cpu0: Intel(R) Core(TM)2 Duo CPU L7300 @ 1.40GHz, 1596.29 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,DTES64,MWAIT,DS-CPL,VMX,EST,TM2,SSSE3,CX16,xTPR,PDCM,NXE,LONG,LAHF,PERF
cpu0: 4MB 64b/line 16-way L2 cache
cpu0: smt 0, core 0, package 0
mtrr: Pentium Pro MTRR support, 8 var ranges, 88 fixed ranges
cpu0: apic clock running at 199MHz
cpu0: mwait min=64, max=64, C-substates=0.2.2.2.2, IBE
cpu1 at mainbus0: apid 1 (application processor)
cpu1: Intel(R) Core(TM)2 Duo CPU L7300 @ 1.40GHz, 1396.50 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,DTES64,MWAIT,DS-CPL,VMX,EST,TM2,SSSE3,CX16,xTPR,PDCM,NXE,LONG,LAHF,PERF
cpu1: 4MB 64b/line 16-way L2 cache
cpu1: smt 0, core 1, package 0
ioapic0 at mainbus0: apid 1 pa 0xfec00000, version 20, 24 pins
ioapic0: misconfigured as apic 2, remapped to apid 1
acpimcfg0 at acpi0 addr 0xf0000000, bus 0-63
acpihpet0 at acpi0: 14318179 Hz
acpiprt0 at acpi0: bus 0 (PCI0)
acpiprt1 at acpi0: bus -1 (AGP_)
acpiprt2 at acpi0: bus 2 (EXP0)
acpiprt3 at acpi0: bus 3 (EXP1)
acpiprt4 at acpi0: bus -1 (EXP2)
acpiprt5 at acpi0: bus -1 (EXP3)
acpiprt6 at acpi0: bus -1 (EXP4)
acpiprt7 at acpi0: bus 5 (PCI1)
acpicpu0 at acpi0: C3, C2, C1, PSS
acpicpu1 at acpi0: C3, C2, C1, PSS
acpipwrres0 at acpi0: PUBS, resource for USB0, USB2, USB4, EHC0, EHC1
acpitz0 at acpi0: critical temperature is 127 degC
acpitz1 at acpi0: critical temperature is 100 degC
acpibtn0 at acpi0: LID_
acpibtn1 at acpi0: SLPB
acpibat0 at acpi0: BAT0 model "93P5030" serial 92 type LION oem "SANYO"
acpibat1 at acpi0: BAT1 not present
acpibat2 at acpi0: BAT2 not present
acpiac0 at acpi0: AC unit online
acpithinkpad0 at acpi0
acpidock0 at acpi0: GDCK not docked (0)
cpu0: Enhanced SpeedStep 1596 MHz: speeds: 1401, 1400, 1200, 800 MHz
pci0 at mainbus0 bus 0
pchb0 at pci0 dev 0 function 0 "Intel GM965 Host" rev 0x0c
vga1 at pci0 dev 2 function 0 "Intel GM965 Video" rev 0x0c
intagp0 at vga1
agp0 at intagp0: aperture at 0xe0000000, size 0x10000000
inteldrm0 at vga1
drm0 at inteldrm0
inteldrm0: 1024x768
wsdisplay0 at vga1 mux 1: console (std, vt100 emulation)
wsdisplay0: screen 1-5 added (std, vt100 emulation)
"Intel GM965 Video" rev 0x0c at pci0 dev 2 function 1 not configured
em0 at pci0 dev 25 function 0 "Intel ICH8 IGP M AMT" rev 0x03: msi, address
00:16:d3:3e:0d:a6
uhci0 at pci0 dev 26 function 0 "Intel 82801H USB" rev 0x03: apic 1 int 20
uhci1 at pci0 dev 26 function 1 "Intel 82801H USB" rev 0x03: apic 1 int 21
ehci0 at pci0 dev 26 function 7 "Intel 82801H USB" rev 0x03: apic 1 int 22
usb0 at ehci0: USB revision 2.0
uhub0 at usb0 "Intel EHCI root hub" rev 2.00/1.00 addr 1
azalia0 at pci0 dev 27 function 0 "Intel 82801H HD Audio" rev 0x03: msi
azalia0: codecs: Analog Devices AD1984, Conexant/0x2bfa, using Analog
Devices AD1984
audio0 at azalia0
ppb0 at pci0 dev 28 function 0 "Intel 82801H PCIE" rev 0x03: msi
pci1 at ppb0 bus 2
ppb1 at pci0 dev 28 function 1 "Intel 82801H PCIE" rev 0x03: msi
pci2 at ppb1 bus 3
wpi0 at pci2 dev 0 function 0 "Intel PRO/Wireless 3945ABG" rev 0x02: msi,
MoW2, address 00:1b:77:2e:0a:42
uhci2 at pci0 dev 29 function 0 "Intel 82801H USB" rev 0x03: apic 1 int 16
uhci3 at pci0 dev 29 function 1 "Intel 82801H USB" rev 0x03: apic 1 int 17
ehci1 at pci0 dev 29 function 7 "Intel 82801H USB" rev 0x03: apic 1 int 19
usb1 at ehci1: USB revision 2.0
uhub1 at usb1 "Intel EHCI root hub" rev 2.00/1.00 addr 1
ppb2 at pci0 dev 30 function 0 "Intel 82801BAM Hub-to-PCI" rev 0xf3
pci3 at ppb2 bus 5
cbb0 at pci3 dev 0 function 0 "Ricoh 5C476 CardBus" rev 0xba: apic 1 int 16
"Ricoh 5C832 Firewire" rev 0x04 at pci3 dev 0 function 1 not configured
sdhc0 at pci3 dev 0 function 2 "Ricoh 5C822 SD/MMC" rev 0x21: apic 1 int 18
sdmmc0 at sdhc0
cardslot0 at cbb0 slot 0 flags 0
cardbus0 at cardslot0: bus 6 device 0 cacheline 0x0, lattimer 0xb0
pcmcia0 at cardslot0
pcib0 at pci0 dev 31 function 0 "Intel 82801HEM LPC" rev 0x03
pciide0 at pci0 dev 31 function 2 "Intel 82801HBM SATA" rev 0x03: DMA,
channel 0 wired to compatibility, channel 1 wired to compatibility
wd0 at pciide0 channel 0 drive 0: <WDC WD5000BEVT-00A0RT0>
wd0: 16-sector PIO, LBA48, 476940MB, 976773168 sectors
wd0(pciide0:0:0): using PIO mode 4, Ultra-DMA mode 6
ichiic0 at pci0 dev 31 function 3 "Intel 82801H SMBus" rev 0x03: apic 1 int
23
iic0 at ichiic0
usb2 at uhci0: USB revision 1.0
uhub2 at usb2 "Intel UHCI root hub" rev 1.00/1.00 addr 1
usb3 at uhci1: USB revision 1.0
uhub3 at usb3 "Intel UHCI root hub" rev 1.00/1.00 addr 1
usb4 at uhci2: USB revision 1.0
uhub4 at usb4 "Intel UHCI root hub" rev 1.00/1.00 addr 1
usb5 at uhci3: USB revision 1.0
uhub5 at usb5 "Intel UHCI root hub" rev 1.00/1.00 addr 1
isa0 at pcib0
isadma0 at isa0
pckbc0 at isa0 port 0x60/5
pckbd0 at pckbc0 (kbd slot)
pckbc0: using irq 1 for kbd slot
wskbd0 at pckbd0: console keyboard, using wsdisplay0
pms0 at pckbc0 (aux slot)
pckbc0: using irq 12 for aux slot
wsmouse0 at pms0 mux 0
pcppi0 at isa0 port 0x61
spkr0 at pcppi0
aps0 at isa0 port 0x1600/31
ugen0 at uhub2 port 2 "STMicroelectronics Biometric Coprocessor" rev
1.00/0.01 addr 2
vscsi0 at root
scsibus1 at vscsi0: 256 targets
softraid0 at root
scsibus2 at softraid0: 256 targets
root on wd0a (efc93098b8f591c3.a) swap on wd0b dump on wd0b
WARNING: / was not properly unmounted
softraid0: sd0 was not shutdown properly
softraid0: sd0 was not shutdown properly
sd0 at scsibus2 targ 1 lun 0: <OPENBSD, SR CRYPTO, 005> SCSI2 0/direct fixed
sd0: 331423MB, 512 bytes/sector, 678755312 sectors
umass0 at uhub1 port 2 configuration 1 interface 0 "TOSHIBA TransMemory"
rev 2.00/1.00 addr 2
umass0: using SCSI over Bulk-Only
scsibus3 at umass0: 2 targets, initiator 0
sd1 at scsibus3 targ 1 lun 0: <TOSHIBA, TransMemory, PMAP> SCSI0 0/direct
removable serial.09306545EB70742C0008
sd1: 61052MB, 512 bytes/sector, 125034496 sectors
uchcom0 at uhub4 port 1 "QinHeng Electronics CH341 serial/parallel" rev
1.10/2.50 addr 2
uchcom0: CH340
ucom0 at uchcom0
