Hi,

Currently the register buffer of gdb in Emacs displays all the registers.
It would be nice if we can select some registers and ask gdb to only
display these. I added this feature in the following patch. For you
convenience I didn't modify the Emacs source but created a new file so you
can just load it and see the effect.

With the extension we can use `gdb-registers-add-to-display' to add
registers to display. And use `gdb-registers-remove-from-display' to remove
registers. Please see more details in the docstring. Change will be visible
in the next update, e.g. after "si" in gdb.

This is just a demo and there are many parts to complete, e.g., naming of
interactive commands, change defvar to defcustom, docsting wording, update
registers immediatly after `add-to-/remove-from-display*', *etc. I want to
know what do you think before going further.

Yuan