1e9fa73016
When debugging multi-threaded programs, QEMU's gdb stub would report the correct number of threads (the qfThreadInfo and qsThreadInfo packets). However, the stub was unable to actually switch between threads (the T packet), since it would report every thread except the first as being dead. Furthermore, the stub relied upon cpu_index as a reliable means of assigning IDs to the threads. This was a bad idea; if you have this sequence of events: initial thread created new thread #1 new thread #2 thread #1 exits new thread #3 thread #3 will have the same cpu_index as thread #1, which would confuse GDB. (This problem is partly due to the remote protocol not having a good way to send thread creation/destruction events.) We fix this by using the host thread ID for the identifier passed to GDB when debugging a multi-threaded userspace program. The thread ID might wrap, but the same sort of problems with wrapping thread IDs would come up with debugging programs natively, so this doesn't represent a problem. Signed-off-by: Nathan Froyd <froydnj@codesourcery.com>
Read the documentation in qemu-doc.html. Fabrice Bellard.