ctx subcommand

The ctx subcommand is used to switch between cpu contexts when viewing a system memory dump.

Note: This subcommand is only available within the kdb command. It cannot be used with the KDB kernel debugger.

Format

ctx [cpu number]

Parameters

Item	Description
cpu number	decimal value or expression indicating a CPU number. If the CPU number is not given as an parameter, the initial context is restored.

Note: You can select KDB context to see more information through the stack trace subcommand. For example, you could see a complete stack of a kernel panic. However, KDB context is available only if the running kernel is booted with KDB kernel debugger.

Other

context

Examples

The following is an example of how to use the ctx subcommand:

$ kdb dump unix  //dump analysis
Preserving 628325 bytes of symbol table
First symbol sys_resource
Component Names:
 1)  proc
 2)  thrd
 3)  errlg
 4)  bos
 5)  vmm
 6)  bscsi
 7)  scdisk
 8)  lvm
 9)  tty
10)  netstat
11)  lent_dd

PFT:
id....................0007
raddr.....0000000001000000 eaddr.....0000000001000000
size..............00800000 align.............00800000
valid..1 ros....0 holes..0 io.....0 seg....1 wimg...2

PVT:
id....................0008
raddr.....00000000004B8000 eaddr.....00000000004B8000
size..............000FFD60 align.............00001000
valid..1 ros....0 holes..0 io.....0 seg....1 wimg...2
Dump analysis on POWER_PC POWER_604 machine with 8 cpu(s)
Processing symbol table...
.......................done
(0)> stat     //machine status
RS6K_SMP_MCA POWER_PC POWER_604 machine with 8 cpu(s)
.......... SYSTEM STATUS
sysname... AIX        nodename.. jumbo32
release... 3          version... 4
machine... 00920312A0 nid....... 920312A0
time of crash: Tue Jul 22 09:46:22 1997
age of system: 1 day, 0 min., 35 sec.
.......... PANIC STRING
assert(v_lookup(sid,pno) == -1)
.......... SYSTEM MESSAGES
AIX 6.1
Starting physical processor #1 as logical #1... done.
Starting physical processor #2 as logical #2... done.
Starting physical processor #3 as logical #3... done.
Starting physical processor #4 as logical #4... done.
Starting physical processor #5 as logical #5... done.
Starting physical processor #6 as logical #6... done.
Starting physical processor #7 as logical #7... done.
[v_lists.c #727]
<- end_of_buffer
(0)> ctx 0     //KDB context of CPU 0
Switch to KDB context of cpu 0
(0)> dr iar     //current instruction
iar   : 00009414
.unlock_enable+000110      lwz    r0,8(stkp)          r0=0,8(stkp)=mststack+00AD18
(0)> ctx 1     //KDB context of CPU 1
Switch to KDB context of cpu 1
(1)> dr iar     //current instruction
iar   : 000BDB68
.kunlockl+000118      blr                        <.ld_usecount+0005BC> r3=0000000B
(1)> ctx 2     //KDB context of CPU 2
Switch to KDB context of cpu 2
(2)> dr iar     //current instruction
iar   : 00027634
.tstart+000284      blr                        <.sys_timer+000964> r3=00000005
(2)> ctx 3     //KDB context of CPU 3
Switch to KDB context of cpu 3
(3)> dr iar     //current instruction
iar   : 01B6A580
01B6A580      ori    r3,r31,0            <00000089> r3=50001000,r31=00000089
(3)> ctx 4     //KDB context of CPU 4
Switch to KDB context of cpu 4
(4)> dr iar     //current instruction
iar   : 00014BFC
.panic_trap+000004       bl    <.panic_dump>       r3=_$STATIC+000294
(4)> f     //current stack
__kdb_thread+0002F0 STACK:
[00014BFC].panic_trap+000004 ()
[0003ACAC]v_inspft+000104 (??, ??, ??)
[00048DA8]v_inherit+0004A0 (??, ??, ??)
[000A7ECC]v_preinherit+000058 (??, ??, ??)
[00027BFC]begbt_603_patch_2+000008 (??, ??)

Machine State Save Area [2FF3B400]
iar   : 00027AEC  msr   : 000010B0  cr    : 22222222  lr    : 00243E58
ctr   : 00000000  xer   : 00000000  mq    : 00000000
r0  : 000A7E74  r1  : 2FF3B220  r2  : 002EBC70  r3  : 00013350  r4  : 00000000
r5  : 00000100  r6  : 00009030  r7  : 2FF3B400  r8  : 00000106  r9  : 00000000
r10 : 00243E58  r11 : 2FF3B400  r12 : 000010B0  r13 : 000C1C80  r14 : 2FF22A88
r15 : 20022DB8  r16 : 20006A98  r17 : 20033128  r18 : 00000000  r19 : 0008AD56
r20 : B02A6038  r21 : 0000006A  r22 : 00000000  r23 : 0000FFFF  r24 : 00000100
r25 : 00003262  r26 : 00000000  r27 : B02B8AEC  r28 : B02A9F70  r29 : 00000001
r30 : 00003350  r31 : 00013350
s0  : 00000000  s1  : 007FFFFF  s2  : 0000864B  s3  : 007FFFFF  s4  : 007FFFFF
s5  : 007FFFFF  s6  : 007FFFFF  s7  : 007FFFFF  s8  : 007FFFFF  s9  : 007FFFFF
s10 : 007FFFFF  s11 : 00001001  s12 : 00002002  s13 : 6001F01F  s14 : 00004004
s15 : 007FFFFF
prev      00000000 kjmpbuf   00000000 stackfix  00000000 intpri    0B
curid     0008AD56 sralloc   E01E0000 ioalloc   00000000 backt     00
flags     00 tid       00000000 excp_type 00000000
fpscr     00000000 fpeu            01 fpinfo          00 fpscrx    00000000
o_iar     00000000 o_toc     00000000 o_arg1    00000000
excbranch 00000000 o_vaddr   00000000 mstext    00000000
Except :
 csr   00000000 dsisr 40000000  bit set: DSISR_PFT
 srval 6000864B dar   2FF22FF8 dsirr 00000106

[00027AEC].backt+000000 (00013350, 00000000 [??])
[00243E54]vms_delete+0004DC (??)
[00256838]shmfreews+0000B0 ()
[000732B4]freeuspace+000010 ()
[00072EAC]kexitx+000688 (??)
(4)> ctx    //AIX context of CPU 4
Restore initial context
(4)> f     //current stack
thread+031920 STACK:
[00027AEC].backt+000000 (00013350, 00000000 [??])
[00243E54]vms_delete+0004DC (??)
[00256838]shmfreews+0000B0 ()
[000732B4]freeuspace+000010 ()
[00072EAC]kexitx+000688 (??)
(4)>