Opcode for filling unused memory

Leo Havmoeller

The 55x FAQ (http://processors.wiki.ti.com/index.php/55x_FAQ#How_do_I_use_Software_Breakpoint_.28estop_1.29_to_debug_my_code.3F) suggest filling unused memory with E_STOP opcodes (0x460c), but E_STOP is a NOP when a debugger is not connected.

Can someone suggest a better fill value?

0 HRi over 12 years ago

Guru 10750 points

Hi Leo,

The ESTOP_1 is very useful when working with the debugger but will not do anything otherwise (The same as NOP) so it could be a very good fill value,

Thanks,

0 Leo Havmoeller over 12 years ago in reply to HRi

What I want is a fill value that causes a predictable program execution exeception both with and without the debugger.

E.g. an exception/trap opcode, or a defined invalid opcode.

0 Bill Finger over 12 years ago in reply to Leo Havmoeller

Genius 3735 points

I recommend the TRAP k instruction.

This is a non-maskable software trap. The op-code is 1001 0101 1xxk kkkk, or in other words (0x9580 | k).

The variable k represents the trap to visit. Be sure to install a helpful trap handler.

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