This is a discussion on double panic, and whats apic_cmd? (kqemu crash...) - FreeBSD ; Ok I finally have an amd64 smp box here that i can play with, and tried to reproduce http://www.freebsd.org/cgi/query-pr.cgi?pr=113430 - and I got the following crash: iapetus# kgdb kernel.debug /var/crash/vmcore.0 [GDB will not be able to debug user-mode threads: /usr/lib/libthread_db.so: ...
Ok I finally have an amd64 smp box here that i can play with, and tried
to reproduce http://www.freebsd.org/cgi/query-pr.cgi?pr=113430 - and I got
the following crash:
iapetus# kgdb kernel.debug /var/crash/vmcore.0
[GDB will not be able to debug user-mode threads: /usr/lib/libthread_db.so: Undefined symbol "ps_pglobal_lookup"]
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This GDB was configured as "amd64-marcel-freebsd".
Unread portion of the kernel message buffer:
Fatal trap 12: page fault while in kernel mode
cpuid = 1; apic id = 01
fault virtual address = 0x1
fault code = supervisor read data, page not present
instruction pointer = 0x8:0xffffffff804e4fa2
stack pointer = 0x10:0xffffffff9fd27530
frame pointer = 0x10:0xffffffff9fd276a0
code segment = base 0x0, limit 0xfffff, type 0x1b
= DPL 0, pres 1, long 1, def32 0, gran 1
processor eflags = interrupt enabled, resume, IOPL = 0
current process = 43 (acpi_thermal)
trap number = 12
panic: page fault
cpuid = 1
KDB: stack backtrace:
db_trace_self_wrapper() at db_trace_self_wrapper+0x2a
panic() at panic+0x17a
trap_fatal() at trap_fatal+0x29f
trap_pfault() at trap_pfault+0x22d
trap() at trap+0x300
calltrap() at calltrap+0x8
--- trap 0xc, rip = 0xffffffff804e4fa2, rsp = 0xffffffff9fd27530, rbp = 0xffffffff9fd276a0 ---
strlen() at strlen+0x2
dmapbase() at 0xffffff00020e6ca8
Physical memory: 986 MB
Dumping 114 MB: 99 83 67 51 35 19 3
#0 doadump () at pcpu.h:194
194 __asm __volatile("movq %%gs:0,%0" : "=r" (td));
#0 doadump () at pcpu.h:194
#1 0xffffffff8046572f in boot (howto=260) at ../../../kern/kern_shutdown.c:409
#2 0xffffffff80465b47 in panic (fmt=Variable "fmt" is not available.
) at ../../../kern/kern_shutdown.c:563
#3 0xffffffff806bc0bf in trap_fatal (frame=0xc, eva=Variable "eva" is not available.
#4 0xffffffff806bc43d in trap_pfault (frame=0xffffffff9fd27480, usermode=0)
#5 0xffffffff806bcd30 in trap (frame=0xffffffff9fd27480)
#6 0xffffffff806a371e in calltrap () at ../../../amd64/amd64/exception.S:169
#7 0xffffffff804e4fa2 in strlen (str=0x1 )
#8 0xffffffff8048c5f5 in kvprintf (
fmt=0xffffffff807aee73 " while in %s mode\n",
, arg=0xffffffff9fd276b0, radix=10, ap=Variable "ap" is not available.
#9 0xffffff00020e6ca8 in ?? ()
#10 0x0000000000000008 in ?? ()
#11 0x0000000000000153 in ?? ()
#12 0xffffffff807add18 in apic_cmd ()
#13 0x0000000000000000 in ?? ()
#14 0xffffffff9fd27700 in ?? ()
#15 0xffffffff8045c28f in _mtx_lock_flags (m=0xffffffff8049668b,
to continue, or q to quit---
opts=36477624, file=0xffffffff9fd276d0 "", line=-2137032800)
Previous frame inner to this frame (corrupt stack?)
" while in %s mode\n" seems to come from /sys/amd64/amd64/trap.c so it's
a double panic, but what is apic_cmd? And what does one do with a double
For anyone who wants to reproduce it (you need an amd64 smp box, mine
runs 7.0beta2), I installed the qemu-devel port with kqemu selected in
config and then ran it in X like
qemu -cdrom sidux.iso -m 256
, booted its grub, quickly switched to a texconsole, just in time for the
panic (sidux is a linux livecd but I guess almost any guest will do, probably
also a freebsd install iso... and maybe if you don't have X you can
get away with a qemu built with sdl/x deselected and then running that with
-nographic. Of course you won't see guest output then so it will have to
boot by itslef, unless it talks to a serial console...)
Btw, to get meaningful backtraces on amd64 I think you need to
rebuild the debug kernel with ddb compiled in, otherwise stuff is left
built with -fomit-frame-pointer which makes gdb unhappy. (shouldn't
-fomit-frame-pointer be disabled for any kind of debug kernel because
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