Date: Sat, 24 Apr 1999 14:10:57 +0930 (CST) From: Greg Lehey <grog@lemis.com> To: FreeBSD-gnats-submit@FreeBSD.org Subject: kern/11299: Recent kernels have broken symbol tables, confusing gdb Message-ID: <199904240440.OAA09541@freebie.lemis.com>
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>Number: 11299
>Category: kern
>Synopsis: Recent kernels have broken symbol tables, confusing gdb
>Confidential: no
>Severity: serious
>Priority: high
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Fri Apr 23 21:50:01 PDT 1999
>Closed-Date:
>Last-Modified:
>Originator: Greg Lehey
>Release: FreeBSD-4.0-CURRENT
>Organization:
LEMIS
>Environment:
4.0-CURRENT after about mid-April
>Description:
I've just had a strange experience. I have some gdb macros which I
use for debugging Vinum. One, ps, gives me a ps-like listing:
(kgdb) ps
Check your .gdbinit, it contains a y command
pid proc addr uid ppid pgrp flag stat comm wchan
1544 c68a5100 c6df3000 0 1534 1544 004006 2 Vinum
1534 c68a57e0 c6ddb000 0 1524 1534 004086 3 bash wait c68a57e0
1524 c68a5c00 c6dc9000 1004 1516 1524 004086 3 bash wait c68a5c00
Another macro helps me load symbols from a kld:
Without:
(kgdb) bt
#0 Debugger (msg=0xc11696a0 "vinum debug") at ../../i386/i386/db_interface.c:318
#1 0xc1163585 in ?? ()
#2 0xc01826ea in spec_ioctl (ap=0xc6df4e1c) at ../../miscfs/specfs/spec_vnops.c:440
With:
(kgdb) bt
#0 Debugger (msg=0xc11696a0 "vinum debug") at ../../i386/i386/db_interface.c:318
#1 0xc1163585 in vinumioctl (dev=0x40001901, cmd=0xc008464b, data=0xc6df4ee0 "", flag=0x3, p=0xc68a5100)
at /src/PANIC/src/sys/modules/Vinum/../../dev/Vinum/vinumioctl.c:96
#2 0xc01826ea in spec_ioctl (ap=0xc6df4e1c) at ../../miscfs/specfs/spec_vnops.c:440
This has worked quite nicely for some time. Since yesterday, after
building a kernel with newbus support, I get strange messages if I
read in the Vinum symbols before reading in the kernel symbols:
(kgdb) bt
#0 Debugger (msg=0xc11696a0 "vinum debug") at ../../i386/i386/db_interface.c:318
#1 0xc1163585 in vinumioctl (dev=0x40001901, cmd=0xc008464b, data=0xc6df4ee0 "", flag=0x3, p=0xc68a5100)
at /src/PANIC/src/sys/modules/Vinum/../../dev/Vinum/vinumioctl.c:96
During symbol reading, "repeated" header file opt_global.h not previously seen, at symtab pos 23.
During symbol reading, Invalid symbol data: type number (2,2) out of range at symtab pos 25..
#2 0xc01826ea in spec_ioctl (ap=0xc6df4e1c) at ../../miscfs/specfs/spec_vnops.c:440
The following stack frames also look strange:
#5 0xc017ccdd in vn_ioctl (fp=<error type>, com=<incomplete type>, data=<incomplete type>, p=<error type>)
at vnode_if.h:395
#6 0xc015c5f7 in ioctl (p=0xc68a5100, uap=0xc6df4f94) at ../../kern/sys_generic.c:564
#7 0xc021e916 in syscall (frame=<error type>) at ../../i386/i386/trap.c:1071
I debugged gdb and found that it was finding these references
(opt_global.h) in cd9660_rrip.o, which it read after reading the Vinum
kld symbols. If I can convince it to read the kernel symbols first, I
don't have any trouble. I don't think that it's anything to do with
that particular file; there must be about 30 files in a typical kernel
build which refer to this symbol.
>How-To-Repeat:
See above. The "ps" macro is in
/usr/src/sys/modules/vinum/.gdbinit.kernel, and the "asf"
macro which loads the symbols of the vinum kld is in
/usr/src/sys/modules/vinum/.gdbinit.vinum.paths. It's
probably easiest to start vinum: just run vinum(8) without any
parameters, and then enter:
# vinum
vinum -> debug 256
vinum -> debug
This will cause gdb to go into serial debugging mode. It
would also probably be possible to do this with gdb against
/dev/mem. If anybody proposes to try it this way, contact me
and we'll discuss what is needed.
>Fix:
Not investigated.
>Release-Note:
>Audit-Trail:
>Unformatted:
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