gdbserver does not work correctly

Hi everyone:

I have a program, which uses LJMP instruction to switch from i386 to
amd64 (both in Linux), and GDB does not support this architecture
switch, but we have fixed this problem, and everything goes well, the
registers' values are correct and 'disas'  command also works well
after 'set architecture i386:x86_64', but when we compile a gdbserver,
and use it to debug a remote target(and this target is just the same
as the program we test early, which we used as a local target), it
cannot work well. Almost every registers' values are wrong, and all
the new registers, such as R8-R15, are assigned as 0, RIP is 0 also.
does anyone familiar with this problem? or does anyone know which
piece of source code I should see.

Thanks.