21.4.4 MIPS
Alpha- and MIPS-based computers use an unusual stack frame, which
sometimes requires gdb to search backward in the object code to
find the beginning of a function.
To improve response time (especially for embedded applications, where
gdb may be restricted to a slow serial line for this search)
you may want to limit the size of this search, using one of these
commands:
set heuristic-fence-post limit- Restrict gdb to examining at most limit bytes in its
search for the beginning of a function. A value of 0 (the
default) means there is no limit. However, except for 0, the
larger the limit the more bytes
heuristic-fence-post must search
and therefore the longer it takes to run. You should only need to use
this command when debugging a stripped executable.
show heuristic-fence-post- Display the current limit.
These commands are available only when gdb is configured
for debugging programs on Alpha or MIPS processors.
Several MIPS-specific commands are available when debugging MIPS
programs:
set mips abi arg- Tell gdb which MIPS ABI is used by the inferior. Possible
values of arg are:
- ‘auto’
- The default ABI associated with the current binary (this is the
default).
- ‘o32’
- ‘o64’
- ‘n32’
- ‘n64’
- ‘eabi32’
- ‘eabi64’
show mips abi- Show the MIPS ABI used by gdb to debug the inferior.
set mips compression arg- Tell gdb which MIPS compressed
ISA (Instruction Set Architecture) encoding is used by the
inferior. gdb uses this for code disassembly and other
internal interpretation purposes. This setting is only referred to
when no executable has been associated with the debugging session or
the executable does not provide information about the encoding it uses.
Otherwise this setting is automatically updated from information
provided by the executable.
Possible values of arg are ‘mips16’ and ‘micromips’.
The default compressed ISA encoding is ‘mips16’, as
executables containing MIPS16 code frequently are not
identified as such.
This setting is “sticky”; that is, it retains its value across
debugging sessions until reset either explicitly with this command or
implicitly from an executable.
The compiler and/or assembler typically add symbol table annotations to
identify functions compiled for the MIPS16 or
microMIPS ISAs. If these function-scope annotations
are present, gdb uses them in preference to the global
compressed ISA encoding setting.
show mips compression- Show the MIPS compressed ISA encoding used by
gdb to debug the inferior.
set mipsfpushow mipsfpu- See set mipsfpu.
set mips mask-address arg- This command determines whether the most-significant 32 bits of 64-bit
MIPS addresses are masked off. The argument arg can be
‘on’, ‘off’, or ‘auto’. The latter is the default
setting, which lets gdb determine the correct value.
show mips mask-address- Show whether the upper 32 bits of MIPS addresses are masked off or
not.
set remote-mips64-transfers-32bit-regs- This command controls compatibility with 64-bit MIPS targets that
transfer data in 32-bit quantities. If you have an old MIPS 64 target
that transfers 32 bits for some registers, like sr and fsr,
and 64 bits for other registers, set this option to ‘on’.
show remote-mips64-transfers-32bit-regs- Show the current setting of compatibility with older MIPS 64 targets.
set debug mips- This command turns on and off debugging messages for the MIPS-specific
target code in gdb.
show debug mips- Show the current setting of MIPS debugging messages.