Refer to http://lists.llvm.org/pipermail/lldb-dev/2015-August/008024.html for discussion on this topic.
Bare-iron target like YAMON gdb-stub does not support qProcessInfo, qC, qfThreadInfo, Hg and Hc packets. Reply from ‘?’ packet is as simple as ‘S05’. There is no packet which gives us process or threads information. In such cases, assume pid=tid=1.