linux – 调试pthreads需要什么？

我想在我的自定义 Linux发行版上调试pthreads,但我遗漏了一些东西.我的主机是Ubuntu 12.04,我的目标是使用crosstool-NG交叉编译工具集构建的i486自定义嵌入式Linux,其余操作系统由Buildroot制作.

我会列出事实：

>我可以在目标上运行多线程应用程序
> Google Breakpad在目标上运行多线程应用程序时无法创建崩溃报告.当我在主机上运行时,具有完全相同构建的Breakpad库的完全相同的应用程序将成功.
> GDB无法调试目标上的多线程应用程序.

例如

$./gdb -n -ex "thread apply all backtrace" ./a.out --pid 716

dlopen failed on 'libthread_db.so.1' - /lib/libthread_db.so.1: undefined symbol: ps_lgetfpregs
GDB will not be able to debug pthreads.
GNU gdb 6.8

由于this,我认为ps_lgetfpregs不是问题.

>我的crosstool构建创建了libthread_db.so文件,并将其放在目标上.
>我的crosstool构建为我的目标创建了gdb,因此它应该与我在目标上运行的相同库链接.
>如果我在我的主机上运行gdb,对我的测试应用程序,我会得到每个正在运行的线程的回溯.

我怀疑Breakpad的问题与GDB的问题有关,但我无法证实这一点.唯一的共同点是缺少多线程调试.

我的主机和目标之间存在一些重要的区别,使我无法在目标上调试pthread.

有谁知道它是什么？

编辑：

TI的Denys Dmytriyenko说：

Normally,GDB is not very picky and you can mix and match different
versions of gdb and gdbserver. But,unfortunately,if you need to
debug multi-threaded apps,there are some dependencies for specific
APIs…

For example,this is one of the messages you may see if you didn’t
build GDB properly for the thread support:

dlopen failed on ‘libthread_db.so.1’ – /lib/libthread_db.so.1:
undefined symbol: ps_lgetfpregs GDB will not be able to debug
pthreads.

请注意,此错误与我获得的错误相同,但他没有详细介绍如何“正确”构建GDB.

并且GDB FAQ说：

(Q) GDB does not see any threads besides the one in which crash occurred;
or SIGTRAP kills my program when I set a breakpoint.

(A) This frequently
happen on Linux,especially on embedded targets. There are two common
causes:

• you are using glibc,and you have stripped libpthread.so.0

• mismatch between libpthread.so.0 and libthread_db.so.1

GDB itself does
not know how to decode “thread control blocks” maintained by glibc and
considered to be glibc private implementation detail. It uses
libthread_db.so.1 (part of glibc) to help it do so. Therefore,
libthread_db.so.1 and libpthread.so.0 must match in version and
compilation flags. In addition,libthread_db.so.1 requires certain
non-global symbols to be present in libpthread.so.0.

Solution: use
strip –strip-debug libpthread.so.0 instead of strip libpthread.so.0.

我尝试了一个非剥离的libpthread.so.0,但它并没有什么区别.我将调查pthread和thread_db之间的任何不匹配.

dlopen failed on 'libthread_db.so.1' - /lib/libthread_db.so.1: undefined symbol: ps_lgetfpregs
GDB will not be able to debug pthreads.