[Gdb-discuss] How to debug vmlinux and gdb itself at the same time ?

[Daniel Jacobowitz]

This is not the right list to ask GDB questions; redirected to gdb@.

On Wed, Mar 16, 2005 at 10:13:49PM +0800, James Yu wrote:
> 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.

GDB doesn't support those registers; a future version may, but updates
to your kgdb stub would also be required.

> 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 ?

You can debug a GDB doing anything, just like any other program.  For
instance, "gdb --args gdb vmlinux".

-- 
Daniel Jacobowitz
CodeSourcery, LLC