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>Number: 2083 >Category: gdb >Synopsis: gdbserver segfaults: thread getmsg err: no event message for getmsg >Confidential: no >Severity: serious >Priority: medium >Responsible: unassigned >State: open >Class: change-request >Submitter-Id: net >Arrival-Date: Thu Feb 16 00:28:01 GMT 2006 >Closed-Date: >Last-Modified: >Originator: chkr@plauener.de >Release: GNU gdb 6.3 >Organization: >Environment: Linux: 2.6.13.1, ppc gcc: (GCC) 3.3.3 gdb: This GDB was configured as "--host=i686-pc-linux-gnu --target=powerpc-vendor-linux-uclibc" >Description: When debugging remotely a program with several threads, most times the gdbserver crashes with the following output: thread getmsg err: no event message for getmsg Segmentation fault (core dumped) and the corresponding gdb gets an timeout: (gdb) c Continuing. [New Thread 1024] Watchdog has expired. Target detached. Here are some more information about the problem: - it seems that it happens only since I changed to the linux 2.6 kernel - because it works sometimes and sometimes not, I assume a timing critical code path which results in a race condition - turning on debug in gdbserver seems to help a little bit, but not for big processes with lots of threads - http://lists.gnu.org/archive/html/bug-gdb/2003-05/msg00042.html describes a similiar probloem - I've also tried to port the patch from this posting: http://sources.redhat.com/ml/gdb/2005-02/msg00058.html to ppc, it helps a little bit as well, but like the other hack it doesn't solve the problem for big processes with many threads - I've used a small test program which I found on the gdb mailinglist: http://lists.gnu.org/archive/html/bug-gdb/2001-04/msg00042.html to reproduce the problem I know that this problem is a little bit tricky, but I'll do all what I can to help you to solve it. So if you need more information to fix the problem or if you have some ideas where I can start looking at the problem feel free to tell me. Thank you very much, Christian >How-To-Repeat: 1. compile the attached file with -lpthread for the ppc platform 2. start it on a ppc platform with the gdbserver connect with gdb to the remote target 3. "continue" >Fix: >Release-Note: >Audit-Trail: >Unformatted: ----gnatsweb-attachment---- Content-Type: application/octet-stream; name="bar.c" Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename="bar.c" I2luY2x1ZGUgPHN0ZGlvLmg+CiNpbmNsdWRlIDxwdGhyZWFkLmg+CiNpbmNsdWRlIDxzeXMvdHlw ZXMuaD4KI2luY2x1ZGUgPHNpZ25hbC5oPgojaW5jbHVkZSA8dW5pc3RkLmg+Cgp2b2lkKiBwcmlu dF9kaWdpdCh2b2lkKiBhcmcpCnsKICAgIGludCBpLGosZGlnaXQ7CiAgICBkaWdpdCA9IChpbnQp YXJnOwogICAgcHJpbnRmKCJcblBJRFslZF0sVEhSWyVkXTogZGlnaXQ9JWRcbiIsZ2V0cGlkKCks cHRocmVhZF9zZWxmKCksZGlnaXQpOwoKICAgIGZvciAoaT0wOyBpIDwgMTAwMDAwMDsgaSsrKSB7 CiAgICAgICAgc2xlZXAoMSk7CiAgICAgICAgcHJpbnRmKCIlZCIsZGlnaXQpOwogICAgICAgIGZm bHVzaChOVUxMKTsKICAgIH0KfQoKcHRocmVhZF90IHRocmlkWzEwXTsKCmludCBtYWluKGludCBh cmdjLCBjaGFyKiogYXJndikKewogICAgaW50IGk9MDsKICAgIHByaW50ZigiXG5tYWluIHRocmVh ZDpUSFJbJWRdXG4iLHB0aHJlYWRfc2VsZigpKTsKICAgIHNsZWVwKDMpOwogICAgcHRocmVhZF9j cmVhdGUoJnRocmlkW2ldLE5VTEwscHJpbnRfZGlnaXQsKHZvaWQgKilpKTsgIGkrKzsKICAgIHB0 aHJlYWRfY3JlYXRlKCZ0aHJpZFtpXSxOVUxMLHByaW50X2RpZ2l0LCh2b2lkICopaSk7ICBpKys7 CiAgICBwdGhyZWFkX2NyZWF0ZSgmdGhyaWRbaV0sTlVMTCxwcmludF9kaWdpdCwodm9pZCAqKWkp OyAgaSsrOwogICAgcHRocmVhZF9jcmVhdGUoJnRocmlkW2ldLE5VTEwscHJpbnRfZGlnaXQsKHZv aWQgKilpKTsgIGkrKzsKICAgIHB0aHJlYWRfY3JlYXRlKCZ0aHJpZFtpXSxOVUxMLHByaW50X2Rp Z2l0LCh2b2lkICopaSk7ICBpKys7CiAgICBwdGhyZWFkX2NyZWF0ZSgmdGhyaWRbaV0sTlVMTCxw cmludF9kaWdpdCwodm9pZCAqKWkpOyAgaSsrOwogICAgcHRocmVhZF9jcmVhdGUoJnRocmlkW2ld LE5VTEwscHJpbnRfZGlnaXQsKHZvaWQgKilpKTsgIGkrKzsKICAgIHB0aHJlYWRfY3JlYXRlKCZ0 aHJpZFtpXSxOVUxMLHByaW50X2RpZ2l0LCh2b2lkICopaSk7ICBpKys7CiAgICBwdGhyZWFkX2Ny ZWF0ZSgmdGhyaWRbaV0sTlVMTCxwcmludF9kaWdpdCwodm9pZCAqKWkpOyAgaSsrOwoKICAgIHNs ZWVwKDEwMDApOwogICAgcHRocmVhZF9leGl0KDApOwp9CgoKCg==
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