Date: Tue, 3 Dec 2002 16:25:33 -0800 From: Chuck Tuffli <chuck_tuffli@agilent.com> To: freebsd-scsi@freebsd.org Subject: decoding a double fault Message-ID: <20021204002532.GB23841@thegrail.rose.agilent.com>
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I'm developing a CAM driver that works with 4.7-RELEASE and am running
into a double fault. The driver is a KLD which loads and then detects a
device on the loop. After detecting the device, I ran
llama# camcontrol rescan 0:0:0
at which point the system double faults and prints the following on
the console
Fatal double fault:
eip = 0xc0354952
esp = 0xc8b8a000
ebp = 0xc8b8a078
panic: double fault
Debugger("panic")
0xc0354952 is the 3rd instruction into the function alltraps
(i386/i386/exception.s:222)
.globl _alltraps
.type _alltraps,@function
_alltraps:
pushal
pushl %ds
pushl %es
pushl %fs
alltraps_with_regs_pushed:
The backtrace looks like
(kgdb) bt
#0 Debugger (msg=0xc03aec3b "panic") at ../../i386/i386/db_interface.c:319
#1 0xc0211ea0 in panic (fmt=0xc03d9cc3 "double fault")
at ../../kern/kern_shutdown.c:593
#2 0xc03637c7 in dblfault_handler () at ../../i386/i386/trap.c:1004
and the contents of common_tss in frame #2 are
(kgdb) p/x common_tss
$1 = {tss_link = 0x0, tss_esp0 = 0xc8b8dff0, tss_ss0 = 0x10, tss_esp1 = 0x0,
tss_ss1 = 0x0, tss_esp2 = 0x0, tss_ss2 = 0x0, tss_cr3 = 0x0,
tss_eip = 0xc0354952, tss_eflags = 0x10803, tss_eax = 0x0, tss_ecx = 0x0,
tss_edx = 0xc8b8a080, tss_ebx = 0xc7e1bee0, tss_esp = 0xc8b8a000,
tss_ebp = 0xc8b8a078, tss_esi = 0xc, tss_edi = 0x0, tss_es = 0x10,
tss_cs = 0x8, tss_ss = 0x10, tss_ds = 0x10, tss_fs = 0x10, tss_gs = 0x2f,
tss_ldt = 0x0, tss_ioopt = 0x680000}
Is there enough information from the above to figure out what code was
being executed, what address caused the fault, what exception
was the OS handling when the fault occured, etc.? Any suggestions,
including RTFM, are welcomed as long as you also include which manual
I should be reading ;)
--
Chuck Tuffli <chuck_tuffli AT NO_SPAM agilent DOT com>
Agilent Technologies, Storage and Networking
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