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2 The up 8 command moves the debugging context 8 activation levels up
the stack to one of the recursive calls within the user program code.
3 The print r command displays the current value of the variable r,
which is a structure of array elements. Full symbolization is available
for the user program, assuming it was compiled with the -g option.
4 The print r.a[511] command displays the current value of array
element 511 of structure r.
2.1.10 Extracting the Preserved Message Buffer
The preserved message buffer (pmsgbuf) contains information such as
the firmware version, operating system version, pc value, and device
configuration. You can use dbx to extract the preserved message buffer from
a running system or dump files. For example:
(dbx) print *pmsgbuf
struct {
msg_magic = 405601
msg_bufx = 1537
msg_bufr = 1537
msg_bufc = "Alpha boot: available memory from 0x7c6000 to 0x6000000
Tru64 UNIX V5.0; Sun Jan 03 11:20:36 EST 1999
physical memory = 96.00 megabytes.
available memory = 84.57 megabytes.
using 360 buffers containing 2.81 megabytes of memory
tc0 at nexus
scc0 at tc0 slot 7
asc0 at tc0 slot 6
rz1 at scsi0 target 1 lun 0 (LID=0) (DEC RZ25 (C) DEC 0700)
rz2 at scsi0 target 2 lun 0 (LID=1) (DEC RZ25 (C) DEC 0700)
rz3 at scsi0 target 3 lun 0 (LID=2) (DEC RZ26 (C) DEC T384)
rz4 at scsi0 target 4 lun 0 (LID=3) (DEC RRD42 (C) DEC 4.5d)
tz5 at scsi0 target 5 lun 0 (DEC TLZ06 (C)DEC 0374)
scsi1 at tc0 slot 7
fb0 at tc0 slot 8
1280X1024
ln0: DEC LANCE Module Name: PMAD-BA
ln0 at tc0 slot 7
.
.
.
2.1.11 Debugging on SMP Systems
Debugging in an SMP environment can be difficult because an SMP system
optimized for performance keeps the minimum of lock debug information.
The Tru64 UNIX system supports a lock mode to facilitate debugging SMP
locking problems. The lock mode is implemented in the lockmode boot
time system attribute. By default, the lockmode attribute is set to a value
between 0 and 3, depending upon whether the system is an SMP system and
whether the RT_PREEMPTION_OPT attribute is set. (This attribute optimizes
system performance.)
2–10 Kernel Debugging Utilities