gdb.info: MIPS

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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 mipsfpu'
'show mipsfpu'
     Note: 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.