intel_gmch_probe(): Panic on kldload /boot/modules/i915kms.ko [drm-fbsd11.2-kmod 4.11g20200221] #225
Description
This is a pretty old Sony Vaio Z machine with
FreeBSD 11.3-STABLE #0 r356413: Mon Jan 6 23:59:20 CET 2020
saper@radziecki:/usr/obj/usr/src/sys/VAIO amd64
FreeBSD clang version 8.0.1 (tags/RELEASE_801/final 366581) (based on LLVM 8.0.1)
VT(vga): resolution 640x480
CPU microcode: updated from 0x60c to 0x60f
CPU: Intel(R) Core(TM)2 Duo CPU P9500 @ 2.53GHz (2527.06-MHz K8-class CPU)
Origin="GenuineIntel" Id=0x10676 Family=0x6 Model=0x17 Stepping=6
Features=0xbfebfbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CLFLUSH,DTS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,PBE>
Features2=0x8e3fd<SSE3,DTES64,MON,DS_CPL,VMX,SMX,EST,TM2,SSSE3,CX16,xTPR,PDCM,SSE4.1>
AMD Features=0x20100800<SYSCALL,NX,LM>
AMD Features2=0x1<LAHF>
VT-x: HLT,PAUSE
TSC: P-state invariant, performance statistics
It has two cards, Intel GM45 and Nvidia
[ 54.818] (--) PCI: (0:0:2:0) 8086:2a42:104d:9025 rev 7, Mem @ 0xe8400000/4194304, 0xd0000000/268435456, I/O @ 0x00008130/8, BIOS @ 0x????????/65536
[ 54.818] (--) PCI: (0:1:0:0) 10de:06e5:104d:9025 rev 161, Mem @ 0xe4000000/16777216, 0xc0000000/268435456, 0xe2000000/33554432, I/O @ 0x00007000/128, BIOS @ 0x????????/65536
[ 62.297] (--) intel(0): Integrated Graphics Chipset: Intel(R) GM45
Everything works fine with modules from base. Can't upgrade to 12.x due to an issue with uhso(4) driver.
I guess my graphics card is too old to be supported, but still we should not just crash.
When I kldload the module, the system panics:
(kgdb) bt
#0 doadump () at pcpu.h:234
#1 0xffffffff80b154b8 in kern_reboot (howto=260) at /usr/src/sys/kern/kern_shutdown.c:388
#2 0xffffffff80b158d8 in vpanic (fmt=<value optimized out>, ap=<value optimized out>) at /usr/src/sys/kern/kern_shutdown.c:784
#3 0xffffffff80b15713 in panic (fmt=<value optimized out>) at /usr/src/sys/kern/kern_shutdown.c:715
#4 0xffffffff80fa5730 in trap_fatal (frame=<value optimized out>, eva=<value optimized out>) at /usr/src/sys/amd64/amd64/trap.c:899
#5 0xffffffff80fa5779 in trap_pfault (frame=0xfffffe011cec3280, usermode=0) at pcpu.h:234
#6 0xffffffff80fa4e0d in trap (frame=0xfffffe011cec3280) at /usr/src/sys/amd64/amd64/trap.c:438
#7 0xffffffff80f84613 in calltrap () at /usr/src/sys/amd64/amd64/exception.S:288
#8 0xffffffff82d995a0 in readl () from /boot/modules/i915kms.ko
#9 0xffffffff82d994f4 in intel_gmch_probe () from /boot/modules/i915kms.ko
#10 0xffffffff82cc39e2 in i915_gmch_probe () from /boot/modules/i915kms.ko
#11 0xffffffff82cc3677 in i915_ggtt_probe_hw () from /boot/modules/i915kms.ko
#12 0xffffffff82c97450 in i915_driver_init_hw () from /boot/modules/i915kms.ko
#13 0xffffffff82c96dcf in i915_driver_load () from /boot/modules/i915kms.ko
#14 0xffffffff82cea97b in i915_pci_probe () from /boot/modules/i915kms.ko
#15 0xffffffff82eff944 in linux_pci_attach () from /boot/kernel/linuxkpi.ko
#16 0xffffffff80b4efac in device_attach (dev=0xfffff800a34f2c00) at device_if.h:180
#17 0xffffffff80b50b09 in bus_generic_driver_added (dev=0xfffff80003987400, driver=<value optimized out>) at /usr/src/sys/kern/subr_bus.c:2864
#18 0xffffffff80b4ccca in devclass_driver_added (dc=0xfffff80003a23980, driver=0xffffffff82e4fbe8) at bus_if.h:204
#19 0xffffffff80b4cc35 in devclass_add_driver (dc=0xfffff80003a23980, driver=0xffffffff82e4fbe8, pass=2147483647, dcp=0xffffffff82e4fc18) at /usr/src/sys/kern/subr_bus.c:1170
#20 0xffffffff82eff2cb in _linux_pci_register_driver () from /boot/kernel/linuxkpi.ko
#21 0xffffffff82cea898 in i915_init () from /boot/modules/i915kms.ko
#22 0xffffffff82cea7d7 in _module_run () from /boot/modules/i915kms.ko
#23 0xffffffff80ae8c21 in linker_load_module (kldname=<value optimized out>, modname=0x0, parent=0x0, verinfo=<value optimized out>, lfpp=<value optimized out>) at /usr/src/sys/kern/kern_linker.c:234
#24 0xffffffff80aea3df in kern_kldload (td=<value optimized out>, file=<value optimized out>, fileid=0xfffffe011cec3a64) at /usr/src/sys/kern/kern_linker.c:1068
#25 0xffffffff80aea4fb in sys_kldload (td=0xfffff80009fd3620, uap=<value optimized out>) at /usr/src/sys/kern/kern_linker.c:1094
#26 0xffffffff80fa6816 in amd64_syscall (td=0xfffff80009fd3620, traced=0) at src/sys/amd64/amd64/../../kern/subr_syscall.c:132
#27 0xffffffff80f84f20 in fast_syscall_common () at /usr/src/sys/amd64/amd64/exception.S:571
#28 0x000000080087028a in ?? ()
drm-fbsd11.2-kmod 4.11g20200221 has been build from ports with make WITH_DEBUG=true install
I have moved away the base modules from /boot/kernel but still kgdb cannot find symbols in the modules installed from ports.
Analysis
intel_private.registers = NULL;
at
https://github.com/FreeBSDDesktop/kms-drm/blob/drm-v4.11-fbsd11.2/i915/intel_freebsd.c#L101
and then we try to readl():
readl(intel_private.registers + AGP_I810_PGTBL_CTL) &
~AGP_I810_PGTBL_ENABLED;
https://github.com/FreeBSDDesktop/kms-drm/blob/drm-v4.11-fbsd11.2/i915/intel_freebsd.c#L107
AGP_I810_PGTBL_CTL is defined to be 0x2020, and here is what readl() is trying to do:
(kgdb) frame 8
#8 0xffffffff82d995a0 in readl () from /boot/modules/i915kms.ko
(kgdb) disass readl
Dump of assembler code for function readl:
0xffffffff82c92c20 <readl+0>: push %rbp
0xffffffff82c92c21 <readl+1>: mov %rsp,%rbp
0xffffffff82c92c24 <readl+4>: sub $0x10,%rsp
0xffffffff82c92c28 <readl+8>: mov %rdi,-0x8(%rbp)
0xffffffff82c92c2c <readl+12>: mov -0x8(%rbp),%rdi
0xffffffff82c92c30 <readl+16>: mov (%rdi),%eax
0xffffffff82c92c32 <readl+18>: mov %eax,-0xc(%rbp)
0xffffffff82c92c35 <readl+21>: mov -0xc(%rbp),%eax
0xffffffff82c92c38 <readl+24>: add $0x10,%rsp
0xffffffff82c92c3c <readl+28>: pop %rbp
0xffffffff82c92c3d <readl+29>: retq
0xffffffff82c92c3e <readl+30>: xchg %ax,%ax
End of assembler dump.
(kgdb) info reg
rax 0x0 0
rbx 0x0 0
rcx 0x2020 8224
rdx 0xffffffff82e44df3 -2098967053
rsi 0x1 1
rdi 0x2020 8224
rbp 0xfffffe011cec3350 0xfffffe011cec3350
rsp 0xfffffe011cec3340 0xfffffe011cec3340
r8 0xffffffff82e44e04 -2098967036
r9 0xd0000000 3489660928
r10 0xffffffff82e44dd9 -2098967079
r11 0xfffffe011cec3400 -2194243046400
r12 0xfffff800a34d0900 -8793353287424
r13 0xfffff80003987400 -8796032699392
r14 0xfffff80003bb3500 -8796030421760
r15 0xfffff800a34f2c00 -8793353147392
rip 0xffffffff82d995a0 0xffffffff82d995a0 <readl+16>
eflags 0x10282 66178
cs 0x20 32
ss 0x28 40
ds 0x0 0
es 0x0 0
fs 0x0 0
gs 0x0 0
Trying to write to location 0x2020 ends up badly. intel_gmch_probe() looks incomplete to me.