Hello! I'm facing with a strange debugging problem under the fresh (19-Dec-2006) CURRENT on the uniprocessor i386 machine. My kernel config is: ident LYNX machine i386 makeoptions DEBUG=-g options INCLUDE_CONFIG_FILE cpu I686_CPU options SCHED_4BSD options ADAPTIVE_GIANT options PREEMPTION device apic options COMPAT_43 options COMPAT_43TTY options COMPAT_FREEBSD4 options COMPAT_FREEBSD5 options COMPAT_FREEBSD6 options SYSVSHM options SYSVSEM options SYSVMSG options KDB options KDB_TRACE options DDB options DDB_NUMSYM options SYSCTL_DEBUG options KTRACE options KTRACE_REQUEST_POOL=101 options INVARIANTS options INVARIANT_SUPPORT options INET options FAST_IPSEC options IPSEC_FILTERGIF device ether device loop device bpf device ppp options PPP_BSDCOMP options PPP_DEFLATE options PPP_FILTER options IPFIREWALL options IPFIREWALL_VERBOSE options IPFIREWALL_VERBOSE_LIMIT=100 options IPFIREWALL_FORWARD options IPSTEALTH options FFS options SOFTUPDATES options UFS_EXTATTR options UFS_ACL options UFS_DIRHASH options QUOTA options _KPOSIX_PRIORITY_SCHEDULING device pty device crypto device pci device atkbdc device atkbd device psm options KBD_INSTALL_CDEV device vga device splash device sc options SC_HISTORY_SIZE=5000 options SC_TWOBUTTON_MOUSE device ata device atadisk options ATA_STATIC_ID device scbus device da device cd device pass To demonstrate the problem, I've forced an artificial panic from the singleuser mode using the 'sysctl debug.kdb.panic=1' command, and then typing 'panic' from ddb. kgdb against the resulting kernel dump fails to print complete backtrace: (kgdb) where #0 doadump () at pcpu.h:166 #1 0xc04aad4c in boot (howto=260) at /mnt3/usr/CURRENT/src/sys/kern/kern_shutdown.c:411 #2 0xc04aaff7 in panic (fmt=0xc05ffbbf "from debugger") at /mnt3/usr/CURRENT/src/sys/kern/kern_shutdown.c:567 #3 0xc044238e in db_panic (addr=-1068723113, have_addr=0, count=-1, modif=0xe4b4795c "") at /mnt3/usr/CURRENT/src/sys/ddb/db_command.c:433 #4 0xc0442327 in db_command (last_cmdp=0xc0660a04, cmd_table=0x0) at /mnt3/usr/CURRENT/src/sys/ddb/db_command.c:401 #5 0xc04423e2 in db_command_loop () at /mnt3/usr/CURRENT/src/sys/ddb/db_command.c:453 #6 0xc044402d in db_trap (type=3, code=0) at /mnt3/usr/CURRENT/src/sys/ddb/db_main.c:222 #7 0xc04c96d1 in kdb_trap (type=3, code=0, tf=0x0) at /mnt3/usr/CURRENT/src/sys/kern/subr_kdb.c:502 #8 0xc05ddfc1 in trap (frame=0xe4b47aec) at /mnt3/usr/CURRENT/src/sys/i386/i386/trap.c:621 #9 0xc05ca84b in calltrap () at /mnt3/usr/CURRENT/src/sys/i386/i386/exception.s:139 #10 0x00000000 in ?? () Previous frame inner to this frame (corrupt stack?) (kgdb) However, if I turn ddb off with the 'sysctl debug.debugger_on_panic=0' and then obtain a kernel dump via 'sysctl debug.kdb.panic=1', kgdb completely unwinds the stack from the resulting dump: (kgdb) where #0 doadump () at pcpu.h:166 #1 0xc04aad4c in boot (howto=260) at /mnt3/usr/CURRENT/src/sys/kern/kern_shutdown.c:411 #2 0xc04aaff7 in panic (fmt=0xc060d1bd "kdb_sysctl_panic") at /mnt3/usr/CURRENT/src/sys/kern/kern_shutdown.c:567 #3 0xc04c929e in kdb_sysctl_panic (oidp=0xc06435c0, arg1=0x0, arg2=0, req=0xe4b78ba4) at /mnt3/usr/CURRENT/src/sys/kern/subr_kdb.c:182 #4 0xc04b3073 in sysctl_root (oidp=0x0, arg1=0x0, arg2=0, req=0xe4b78ba4) at /mnt3/usr/CURRENT/src/sys/kern/kern_sysctl.c:1282 #5 0xc04b3244 in userland_sysctl (td=0x0, name=0xe4b78c24, namelen=3, old=0xe4b78ba4, oldlenp=0x0, inkernel=0, new=0xbfbfe4bc, newlen=0, retval=0xe4b78c20, flags=0) at /mnt3/usr/CURRENT/src/sys/kern/kern_sysctl.c:1381 #6 0xc04b30fb in __sysctl (td=0xc3cf91b0, uap=0xe4b78d00) at /mnt3/usr/CURRENT/src/sys/kern/kern_sysctl.c:1316 #7 0xc05de786 in syscall (frame=0xe4b78d38) at /mnt3/usr/CURRENT/src/sys/i386/i386/trap.c:1008 #8 0xc05ca8b0 in Xint0x80_syscall () at /mnt3/usr/CURRENT/src/sys/i386/i386/exception.s:196 #9 0x48133747 in ?? () Previous frame inner to this frame (corrupt stack?) I've tried to repeat this under the RELENG_6 as of 30-Oct (just removing kernel options COMPAT_43TTY, COMPAT_FREEBSD6, INVARIANTS, INVARIANT_SUPPORT, and using 'debug.kdb.enter' instead of 'debug.kdb.panic') - and kgdb unwinds the stack even if the dump got via typing 'panic' from ddb: (kgdb) where #0 doadump () at pcpu.h:165 #1 0xc049eb46 in boot (howto=260) at /usr/RELENG_6/src/sys/kern/kern_shutdown.c:409 #2 0xc049ee0c in panic (fmt=0xc05fabc0 "from debugger") at /usr/RELENG_6/src/sys/kern/kern_shutdown.c:565 #3 0xc043fcd5 in db_panic (addr=-1068795853, have_addr=0, count=-1, modif=0xe526ba2c "") at /usr/RELENG_6/src/sys/ddb/db_command.c:438 #4 0xc043fc6c in db_command (last_cmdp=0xc06483a4, cmd_table=0x0, aux_cmd_tablep=0xc061ac3c, aux_cmd_tablep_end=0xc061ac40) at /usr/RELENG_6/src/sys/ddb/db_command.c:350 #5 0xc043fd34 in db_command_loop () at /usr/RELENG_6/src/sys/ddb/db_command.c:458 #6 0xc0441949 in db_trap (type=3, code=0) at /usr/RELENG_6/src/sys/ddb/db_main.c:222 #7 0xc04b7aaf in kdb_trap (type=3, code=0, tf=0xe526bb6c) at /usr/RELENG_6/src/sys/kern/subr_kdb.c:473 #8 0xc05da99c in trap (frame= {tf_fs = -450494456, tf_es = -1068826584, tf_ds = -1067450328, tf_edi = -450446332, tf_esi = 0, tf_ebp = -450446420, tf_isp = -450446440, tf_ebx = -450446332, tf_edx = 0, tf_ecx = -1056878592, tf_eax = 35, tf_trapno = 3, tf_err = 0, tf_eip = -1068795853, tf_cs = 32, tf_eflags = 646, tf_esp = -450446400, tf_ss = -1068796128}) at /usr/RELENG_6/src/sys/i386/i386/trap.c:594 #9 0xc05c915a in calltrap () at /usr/RELENG_6/src/sys/i386/i386/exception.s:139 #10 0xc04b7833 in kdb_enter (msg=0x23 <Address 0x23 out of bounds>) at cpufunc.h:60 #11 0xc04b7720 in kdb_sysctl_enter (oidp=0xc062cf60, arg1=0x0, arg2=0, req=0xe526bc04) at /usr/RELENG_6/src/sys/kern/subr_kdb.c:175 #12 0xc04a6bb3 in sysctl_root (oidp=0x0, arg1=0x0, arg2=0, req=0xe526bc04) at /usr/RELENG_6/src/sys/kern/kern_sysctl.c:1281 #13 0xc04a6db0 in userland_sysctl (td=0x23, name=0xe526bc74, namelen=3, old=0xe526bc04, oldlenp=0x0, inkernel=0, new=0xbfbfe4ac, newlen=35, retval=0xe526bc70, flags=35) at /usr/RELENG_6/src/sys/kern/kern_sysctl.c:1380 #14 0xc04a6c53 in __sysctl (td=0xc4d0ea80, uap=0xe526bd04) at /usr/RELENG_6/src/sys/kern/kern_sysctl.c:1315 #15 0xc05db1f3 in syscall (frame= {tf_fs = 59, tf_es = 59, tf_ds = 59, tf_edi = 3, tf_esi = 0, tf_ebp = -1077943272, tf_isp = -450445980, tf_ebx = 1209310688, tf_edx = 0, tf_ecx = -1077941056, tf_eax = 202, tf_trapno = 12, tf_err = 2, tf_eip = 1209155743, tf_cs = 51, tf_eflags = 658, tf_esp = -1077943332, tf_ss = 59}) at /usr/RELENG_6/src/sys/i386/i386/trap.c:983 #16 0xc05c91af in Xint0x80_syscall () at /usr/RELENG_6/src/sys/i386/i386/exception.s:200 #17 0x00000033 in ?? () So it looks like a regression in CURRENT vs RELENG_6 (either ddb 'spoils' the stack somehow, or kgdb fails to unwind it). Sincerely, Dmitry -- Atlantis ISP, System Administrator e-mail: dmitry_at_atlantis.dp.ua nic-hdl: LYNX-RIPEReceived on Tue Dec 19 2006 - 16:52:37 UTC
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