Re: [Qemu-devel] RFC: Why does target/m68k RTE insn. use gen_exception

[Richard Henderson]

On 6/27/19 3:22 PM, Lucien Anti-Spam wrote:
> Hi Laurent / Richard,
> (resent email )
> 
> Does anyone have any knowledge why
>     gen_exception(s, s->base.pc_next, EXCP_RTE);
> 
> is generated for "RTE" instruction, where as the "RTS" goes a gen_jmp?
> ( note see target/m68k/translate.c in functions DISAS_INSN(rte) and 
> DISAS_INSN(rts)

History, it would seem.  Paul Brook implemented it that way in 2007.

I think that it should not be implemented as an exception.  It should be a call
to one of two different helpers (cf and m68k), followed by either a normal exit
to main loop (to recognize the new interrupt state) or a debug exception.

This sort of modification should be fairly easy to perform, if you have the 
time.


r~