BAT registers are only used to map large sections of
physical memory or I/O space. There are now allocated
on a need-be basis (at least some are) are so gdb
would not need the current or past values. If gdb
needed to access those physical addresses, the kernel wil trap
and replace the corresponding BAT register. You can always
dump the shadow bat table if you need to debug BATS.

-Derek

jacereda@gmail.com wrote:
> Hi,
> 
> I'm trying to bring back IPKDB support. I have some questions:
> 
> - Somewhere in the file is a:
> 
> #define ipkdbsave   0xde0       /* primary save area for IPKDB */
> ...
> ipkdbtrap:
>     FRAME_SETUP(ipkdbsave)
> /* Call C trap code: */
> ...
> 
> Shouldn't that be FRAME_SETUP(CI_IPKDBSAVE) ? That define seems obsolete.
> 
> - Why aren't things like BAT registers saved in the frame? How is gdb
> supossed to get them?
> 
> TIA,
>   Jorge Acereda