wrong PC for "set architecuture xxx" for gdbserver

[fei ding]

Hi:

I use "set architecuture xxx" command to change arch for my gdbserver,
and I've traced that, gdb will send a g_packet to gdbserver to fetch
registers' values, and then do some correct-pc-things.

But, if I input the "set arch xxx" command right after the "continue"
command, the value of EIP will always be wrong, it points to the
instruction after the correct one. Why?