>Synopsis: pcidump -v panics: "pci_conf_read: cannot map mcfg space"
>Category: kernel
>Environment:
System : OpenBSD 8.0
Details : OpenBSD 8.0 (GENERIC.MP) #84: Tue Oct 6 23:13:49 MDT 2026
[email protected]:/usr/src/sys/arch/amd64/compile/GENERIC.MP
Architecture: OpenBSD.amd64
Machine : amd64
>Description:
Running "doas sendbug -P", which runs "pcidump -xxv", panicked the
machine. Transcribed from a photo of the console:
panic: pci_conf_read: cannot map mcfg space
Starting stack trace...
panic(ffffffff826f61b7) at panic+0x170
pci_conf_read(0,8000e000,100) at pci_conf_read+0x16d
Nothing further was printed. Tag 0x8000e000 is 0:28:0, ppb0 "Intel
Bay Trail PCIE"; register 0x100 is PCI_PCIE_ECAP, where pcidump -v
starts walking the extended capability list. acpimcfg0 reports
addr 0xe0000000, bus 0-255, so pci_conf_size() allows the read and
pci_mcfg_map_bus(0) panics when bus_space_map() of 0xe0000000 fails.
A failed mapping reached from the PCIOCREAD ioctl panics rather than
returning an error.
>How-To-Repeat:
pcidump -v (as root) on this machine; observed once.
>Fix:
Unknown.
dmesg:
OpenBSD 8.0 (GENERIC.MP) #84: Tue Oct 6 23:13:49 MDT 2026
[email protected]:/usr/src/sys/arch/amd64/compile/GENERIC.MP
real mem = 8441147392 (8050MB)
avail mem = 8162750464 (7784MB)
random: good seed from bootblocks
mpath0 at root
scsibus0 at mpath0: 256 targets
mainbus0 at root
bios0 at mainbus0: SMBIOS rev. 3.0 @ 0xedab0 (49 entries)
bios0: vendor American Megatrends Inc. version "5.6.5" date 07/22/2022
bios0: Default string RC100/BC100
efi0 at bios0: UEFI 2.4
efi0: American Megatrends rev 0x5000a
acpi0 at bios0: ACPI 5.0
acpi0: sleep states S0 S3 S4 S5
acpi0: tables DSDT FACP APIC FPDT FIDT TCPA LPIT MCFG HPET SSDT SSDT SSDT UEFI
SSDT TPM2 CSRT
acpi0: wakeup devices PS2K(S3) PS2M(S3) XHC1(S4) RP01(S4) PXSX(S4) RP02(S4)
PXSX(S4) RP03(S4) PXSX(S4) RP04(S4) PXSX(S4) PWRB(S0) BRCM(S0)
acpitimer0 at acpi0: 3579545 Hz, 24 bits
acpimadt0 at acpi0 addr 0xfee00000: PC-AT compat
cpu0 at mainbus0: apid 0 (boot processor)
cpu0: Intel(R) Celeron(R) CPU J1900 @ 1.99GHz, 2000.29 MHz, 06-37-09, patch
0000090d
cpu0: cpuid 1
edx=bfebfbff<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>
ecx=41d8e3bf<SSE3,PCLMUL,DTES64,MWAIT,DS-CPL,VMX,EST,TM2,SSSE3,CX16,xTPR,PDCM,SSE4.1,SSE4.2,MOVBE,POPCNT,DEADLINE,RDRAND>
cpu0: cpuid 6 eax=7<SENSOR,ARAT> ecx=9<EFFFREQ>
cpu0: cpuid 7.0 ebx=2282<TSC_ADJUST,SMEP,ERMS>
edx=c000400<MD_CLEAR,IBRS,IBPB,STIBP>
cpu0: cpuid a vers=3, gp=2, gpwidth=40, ff=3, ffwidth=40
cpu0: cpuid 80000001 edx=28100800<NXE,RDTSCP,LONG> ecx=101<LAHF,3DNOWP>
cpu0: cpuid 80000007 edx=100<ITSC>
cpu0: MELTDOWN
cpu0: 24KB 64b/line 6-way D-cache, 32KB 64b/line 8-way I-cache, 1MB 64b/line
16-way L2 cache
cpu0: smt 0, core 0, package 0, type P
mtrr: Pentium Pro MTRR support, 8 var ranges, 88 fixed ranges
cpu0: apic clock running at 83MHz
cpu0: mwait min=64, max=64, C-substates=0.2.0.0.0.0.3.3, IBE
cpu1 at mainbus0: apid 2 (application processor)
cpu1: Intel(R) Celeron(R) CPU J1900 @ 1.99GHz, 2000.47 MHz, 06-37-09, patch
0000090d
cpu1: smt 0, core 1, package 0, type P
cpu2 at mainbus0: apid 4 (application processor)
cpu2: Intel(R) Celeron(R) CPU J1900 @ 1.99GHz, 2000.62 MHz, 06-37-09, patch
0000090d
cpu2: smt 0, core 2, package 0, type P
cpu3 at mainbus0: apid 6 (application processor)
cpu3: Intel(R) Celeron(R) CPU J1900 @ 1.99GHz, 2000.60 MHz, 06-37-09, patch
0000090d
cpu3: smt 0, core 3, package 0, type P
ioapic0 at mainbus0: apid 1 pa 0xfec00000, version 20, 87 pins
acpimcfg0 at acpi0
acpimcfg0: addr 0xe0000000, bus 0-255
acpihpet0 at acpi0: 14318179 Hz
acpiprt0 at acpi0: bus 0 (PCI0)
acpiprt1 at acpi0: bus 1 (RP01)
acpiprt2 at acpi0: bus 2 (RP02)
acpiprt3 at acpi0: bus 3 (RP03)
acpiprt4 at acpi0: bus 4 (RP04)
acpiec0 at acpi0: not present
acpicmos0 at acpi0
acpipci0 at acpi0 PCI0: 0x00000010 0x00000011 0x00000000
"MSFT0001" at acpi0 not configured
"MSFT0003" at acpi0 not configured
com0 at acpi0 UAR1 addr 0x3f8/0x8 irq 4: ns16550a, 16 byte fifo
com0: probed fifo depth: 15 bytes
com1 at acpi0 UAR2 addr 0x2f8/0x8 irq 3: ns16550a, 16 byte fifo
com1: probed fifo depth: 15 bytes
acpibtn0 at acpi0: PWRB(wakeup)
acpibtn1 at acpi0: SLPB
bytgpio0 at acpi0 GPO0 uid 1 addr 0xfed0c000/0x1000 irq 49, 102 pins
bytgpio1 at acpi0 GPO1 uid 2 addr 0xfed0d000/0x1000 irq 48, 28 pins
bytgpio2 at acpi0 GPO2 uid 3 addr 0xfed0e000/0x1000 irq 50, 44 pins
"INTL9C60" at acpi0 not configured
iosf0 at acpi0 MBID
tpm0 at acpi0 TPM_: unsupported TPM2 start method 2
acpicpu0 at acpi0: C3(10@1500 mwait.1@0x52), C2(10@500 mwait.1@0x51), C1(1000@1
mwait.1), PSS
acpicpu1 at acpi0: C3(10@1500 mwait.1@0x52), C2(10@500 mwait.1@0x51), C1(1000@1
mwait.1), PSS
acpicpu2 at acpi0: C3(10@1500 mwait.1@0x52), C2(10@500 mwait.1@0x51), C1(1000@1
mwait.1), PSS
acpicpu3 at acpi0: C3(10@1500 mwait.1@0x52), C2(10@500 mwait.1@0x51), C1(1000@1
mwait.1), PSS
acpipwrres0 at acpi0: PLPE
acpipwrres1 at acpi0: PLPE
acpipwrres2 at acpi0: USBC, resource for EHC1, OTG1
acpipwrres3 at acpi0: CLK0, resource for CAM1
acpipwrres4 at acpi0: CLK1, resource for CAM0, CAM2
acpivideo0 at acpi0: GFX0
acpivout0 at acpivideo0: DD1F
cpu0: using VERW MDS workaround
cpu0: Enhanced SpeedStep 2000 MHz: speeds: 1993, 1992, 1909, 1826, 1743, 1660,
1577, 1494, 1411, 1328 MHz
pci0 at mainbus0 bus 0
iosf1 at pci0 dev 0 function 0 "Intel Bay Trail Host" rev 0x11: mbi
inteldrm0 at pci0 dev 2 function 0 "Intel Bay Trail Video" rev 0x11
drm0 at inteldrm0
inteldrm0: msi, VALLEYVIEW, gen 7
sdhc0 at pci0 dev 18 function 0 "Intel Bay Trail SD/MMC" rev 0x11: apic 1 int 18
sdhc0: SDHC 3.00, 100 MHz base clock
sdmmc0 at sdhc0: 4-bit, sd high-speed, mmc high-speed, ddr52, dma
ahci0 at pci0 dev 19 function 0 "Intel Bay Trail AHCI" rev 0x11: msi, AHCI 1.3
ahci0: port 0: 3.0Gb/s
scsibus1 at ahci0: 32 targets
sd0 at scsibus1 targ 0 lun 0: <ATA, TS128GMSA230S, R042> naa.57c35481d355e8ca
sd0: 122104MB, 512 bytes/sector, 250069680 sectors, thin
xhci0 at pci0 dev 20 function 0 "Intel Bay Trail xHCI" rev 0x11: msi, xHCI 1.0
usb0 at xhci0: USB revision 3.0
uhub0 at usb0 configuration 1 interface 0 "Intel xHCI root hub" rev 3.00/1.00
addr 1
"Intel Bay Trail TXE" rev 0x11 at pci0 dev 26 function 0 not configured
azalia0 at pci0 dev 27 function 0 "Intel Bay Trail HD Audio" rev 0x11: msi
azalia0: codecs: Realtek ALC888, Intel/0x2882, using Realtek ALC888
audio0 at azalia0
ppb0 at pci0 dev 28 function 0 "Intel Bay Trail PCIE" rev 0x11: msi
pci1 at ppb0 bus 1
em0 at pci1 dev 0 function 0 "Intel I210" rev 0x03: msi, address
ac:40:ea:03:5a:46
ppb1 at pci0 dev 28 function 1 "Intel Bay Trail PCIE" rev 0x11: msi
pci2 at ppb1 bus 2
em1 at pci2 dev 0 function 0 "Intel I210" rev 0x03: msi, address
ac:40:ea:03:5a:47
ppb2 at pci0 dev 28 function 2 "Intel Bay Trail PCIE" rev 0x11: msi
pci3 at ppb2 bus 3
ppb3 at pci0 dev 28 function 3 "Intel Bay Trail PCIE" rev 0x11: msi
pci4 at ppb3 bus 4
pcib0 at pci0 dev 31 function 0 "Intel Bay Trail LPC" rev 0x11
ichiic0 at pci0 dev 31 function 3 "Intel Bay Trail SMBus" rev 0x11: apic 1 int
18
iic0 at ichiic0
spdmem0 at iic0 addr 0x50: 8GB DDR3 SDRAM PC3-12800 SO-DIMM
isa0 at pcib0
isadma0 at isa0
pckbc0 at isa0 port 0x60/5 irq 1 irq 12
pckbd0 at pckbc0 (kbd slot)
wskbd0 at pckbd0: console keyboard
pcppi0 at isa0 port 0x61
spkr0 at pcppi0
vmm0 at mainbus0: VMX/EPT (using slow L1TF mitigation)
efifb at mainbus0 not configured
enable mbufs in high memory
sdmmc0: can't enable card
uhub1 at uhub0 port 4 configuration 1 interface 0 "Standard Microsystems
product 0x2514" rev 2.00/b.b3 addr 2
uhub1: port 3, set config 0 at addr 3 failed
uhub1: device problem, disabling port 3
vscsi0 at root
scsibus2 at vscsi0: 256 targets
softraid0 at root
scsibus3 at softraid0: 256 targets
root on sd0a (3a5cea56faa34e64.a) swap on sd0b dump on sd0b
WARNING: / was not properly unmounted
inteldrm0: 2560x1440, 32bpp
wsdisplay0 at inteldrm0 mux 1: console (std, vt100 emulation), using wskbd0
wsdisplay0: screen 1-5 added (std, vt100 emulation)
