Re: gdb & libdata/debug

[Patrick Welche <prlw1%cam.ac.uk@localhost>]

Different computer which has fresh sets. Why can crash do better than gdb?

[I am not convinced that gdb is currently useful - got to the previous
message as I kept getting "registers not found" message just trying to
set a breakpoint in a rump kernel]

# crash -M netbsd.1.core -N netbsd.1
Crash version 9.99.12, image version 9.99.12.
System panicked: kernel diagnostic assertion "fdm != NULL" failed: file "../../../../kern/vfs_trans.c", line 166 mount 0x0 invalid
Backtrace from time of crash is available.
crash> bt
_KERNEL_OPT_NARCNET() at 0
_KERNEL_OPT_ACPI_SCANPCI() at _KERNEL_OPT_ACPI_SCANPCI+0x17
vpanic() at vpanic+0x169
stge_eeprom_wait.isra.4() at stge_eeprom_wait.isra.4
fstrans_alloc_lwp_info() at fstrans_alloc_lwp_info+0x283
fstrans_start() at fstrans_start+0x3f
VOP_LOCK() at VOP_LOCK+0x4c
vn_lock() at vn_lock+0xa1
vn_rdwr() at vn_rdwr+0x136
write_record.part.1() at write_record.part.1+0x54
diff_cb() at diff_cb+0x236
traverse_visitbp() at traverse_visitbp+0x1b6
traverse_visitbp() at traverse_visitbp+0x52b
traverse_visitbp() at traverse_visitbp+0x52b
traverse_visitbp() at traverse_visitbp+0x52b
traverse_visitbp() at traverse_visitbp+0x52b
traverse_visitbp() at traverse_visitbp+0x52b
traverse_dnode() at traverse_dnode+0xda
traverse_visitbp() at traverse_visitbp+0x8ab
traverse_impl() at traverse_impl+0x16c
traverse_dataset_resume() at traverse_dataset_resume+0x44
dmu_diff() at dmu_diff+0x14c
zfs_ioc_diff() at zfs_ioc_diff+0x42
zfsdev_ioctl() at zfsdev_ioctl+0x265
nb_zfsdev_ioctl() at nb_zfsdev_ioctl+0x38
VOP_IOCTL() at VOP_IOCTL+0x54
vn_ioctl() at vn_ioctl+0xa5
sys_ioctl() at sys_ioctl+0x5ab
syscall() at syscall+0x196
--- syscall (number 54) ---
7977bfb7fc7a:


# gdb netbsd.1
GNU gdb (GDB) 8.3
...
Reading symbols from netbsd.1...
(No debugging symbols found in netbsd.1)
(gdb) target kvm netbsd.1.core
0xffffffff80221a55 in cpu_reboot ()
(gdb) bt
#0  0xffffffff80221a55 in cpu_reboot ()
#1  0xffffffff80a29966 in vpanic ()
#2  0xffffffff80e68efb in kern_assert ()
#3  0xffffffff80a8ab58 in fstrans_alloc_lwp_info ()
#4  0xffffffff80a8b2da in fstrans_start ()
#5  0xffffb131d049e890 in ?? ()
#6  0x0000000000000000 in ?? ()


Cheers,

Patrick