Re: debugging kernel threads
At Wed, 26 Jan 2005 10:52:45 +0100,
Richard Nyberg wrote:
>
> I often use gdb's proc command to switch between different processes
> when debugging kernel cores. Now I want to debug a kernel thread
> and it doesn't seem to work. Does anyone know how to switch to a
> kernel thread? Maybe proc could be tweaked to work for threads too.
>
Replying to myself...
I RTFS and it looked like proc should work with kernel threads.
The problem seems to be that the threads td_pcb is invalid.
Example:
(kgdb) psx
....
0 -1 c121d600 00000e00 vnlru c121d600 vlruwt
....
(kgdb) p *((struct thread*)0xc121d600)->td_pcb
$11 = {pcb_cr3 = 0, pcb_edi = 0, pcb_esi = -1071893984, pcb_ebp = 0,
pcb_esp = 0, pcb_ebx = 0, pcb_eip = 0, pcb_dr0 = 0, pcb_dr1 = 0,
pcb_dr2 = 0, pcb_dr3 = 0, pcb_dr6 = 0, pcb_dr7 = 0, pcb_ldt = 0x0,
pcb_save = {sv_87 = {sv_env = {en_cw = 0, en_sw = 0, en_tw = 0, en_fip = 0,
en_fcs = 0, en_opcode = 0, en_foo = 0, en_fos = 0}, sv_ac = {{
fp_bytes = "\000\000\000\000\000\000\000\000\000"}, {
fp_bytes = "\000\000\000\000\000\000\000\000\000"}, {
fp_bytes = "\000\000\000\000\000\000\000\000\000"}, {
fp_bytes = "\000\000\000\000\000\000\000\000\000"}, {
fp_bytes = "\000\000\000\000\000\000\000\000\000"}, {
fp_bytes = "\000\000\000\000\000\000\000\000\000"}, {
fp_bytes = "\000\000\000\000\000\000\000\000\000"}, {
fp_bytes = "\000\000\000\000\000\000\000\000\000"}}, sv_ex_sw = 0,
sv_pad = '\0' <repeats 63 times>}, sv_xmm = {sv_env = {en_cw = 0,
en_sw = 0, en_tw = 0, en_opcode = 0, en_fip = 0, en_fcs = 0,
en_pad0 = 0, en_foo = 0, en_fos = 0, en_pad1 = 0, en_mxcsr = 0,
en_pad2 = 0}, sv_fp = {{fp_acc = {
fp_bytes = "\000\000\000\000\000\000\000\000\000"},
fp_pad = "\000\000\000\000\000"}, {fp_acc = {
fp_bytes = "\000\000\000\000\000\000\000\000\000"},
fp_pad = "\000\000\000\000\000"}, {fp_acc = {
fp_bytes = "\000\000\000\000\000\000\000\000\000"},
fp_pad = "\000\000\000\000\000"}, {fp_acc = {
fp_bytes = "\000\000\000\000\000\000\000\000\000"},
fp_pad = "\000\000\000\000\000"}}, sv_xmm = {{
xmm_bytes = '\0' <repeats 15 times>}, {
xmm_bytes = '\0' <repeats 15 times>}, {
xmm_bytes = '\0' <repeats 15 times>}, {
xmm_bytes = '\0' <repeats 15 times>}, {
xmm_bytes = '\0' <repeats 15 times>}, {
xmm_bytes = '\0' <repeats 15 times>}, {
xmm_bytes = '\0' <repeats 15 times>}, {
xmm_bytes = '\0' <repeats 15 times>}}, sv_ex_sw = 0,
sv_pad = '\0' <repeats 219 times>}}, pcb_flags = 0 '\0',
pcb_onfault = 0x0, pcb_gs = 0, pcb_ext = 0x0, __pcb_spare = {0, 0, 0}}
A random selection of other threads shows similarly broken pcb's.
-Richard
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