How to debug vmlinux and gdb itself at the same time ?

Since current "info all-registers" provided in gdb doesn't output the
values of hardware registers CR0, CR1, CR2, CR3, CR4, GDTR, LDTR and
etc... I backtraced the gdb with gdb itself and tried to see how gdb
retrieves hardware register values, so I can get the content of the
registers previously mentioned myself.

However, when I traced up to "registers_info()" in gdb/infcmd.c:1596,
the first test of "if (!targt_has_registers)" failed. Then I came up
with an idea of debugging a gdb that is debugging a vmlinux (so I'll
have some registers to print out in the inner gdb env), just I don't
know whether it works and how to carry it out.

Or maybe there are other ways to get the registers mentioned above ?

Thanks in advance,
-- 
James Yu (游家慶)
+886-932-353-055
[email protected]