[ltt-dev] UST - Problems in recording trace on a current process

[Naren]

Hi Pierre,

>>So we have the answer to your problem. You cannot list the markers on your
>>program (firefox) because it was not linked with libust. Linking a program
to
>>libust is essential in order to be able to trace it or to list markers.

>>There are two ways of doing this. Either you can link it with the gcc
>>option -lust at compile time, or you can link it at runtime using
LD_PRELOAD.
>>For example:

>>LD_PRELOAD=/path/to/libust.so ./myprogram

I did a LD_PRELOAD on libust.so

Inside /usr/local/lib directory, i found three shared objects with the same
name libust. I guess libust.so is the linker name and libust.so.0 and
libust.so.0.0.0 are fully qualified names with libust.so.0  being linked
to libust.so.0 .0.0 .

Having found that running LD_PRELOAD on libust.so, again unfortunately, gave
this error. Moreover, the other alternative also gave the same one.

>>Another way to do the LD_PRELOAD trick is to use usttrace, which will do
it
>>automatically with -l:

>>usttrace -l ./myprogram

*ERROR: ld.so: object '/usr/local/lib/libust.so' from LD_PRELOAD cannot be
preloaded: ignored.*
*
*
*So, I tried LD_PRELOAD with libust.so.0.0.0, this time i didnt get any
error.*
*
*
*However, ustctl --list-markers pid , I am getting segmentation fault.*
*I did a strace on that, and found these interesting traces.*
*
*
*
socket(PF_FILE, SOCK_STREAM, 0)         = 3
connect(3, {sa_family=AF_FILE, path="/tmp/ust-app-socks/1709"}, 110) = 0
send(3, "list_markers", 12, MSG_NOSIGNAL) = 12
recv(3, "marker: metadata/core_marker_id "..., 1000, 0) = 1000
--- SIGSEGV (Segmentation fault) @ 0 (0) ---
+++ killed by SIGSEGV +++

The full dump of strace can be found here http://pastebin.ca/1792101 .

Is it a problem due to multiple shared objects, or does it necessitate
another clean install of some libraries?

Regards
Naren
*
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.casi.polymtl.ca/pipermail/lttng-dev/attachments/20100210/ceb72a7e/attachment-0002.htm>