At 4:12 Uhr +0100 05.02.1998, Gordon W. Ross wrote:

>It would be nice if we could let a simple "trap #2" do the job of
>flushing the I-cache as needed for self-modifying code to work.
>That's what "trap #2" does on SunOS (their dynamic linker uses it).
>Also it was implemented as a "fast trap" (no "rei" check, just rte)
>so we could do the same and let both our executables and SunOS
>enjoy the availability of a very cheap I-cache flush.
>
>BTW, we no longer use "trap #2" for kernel breakpoints, so we
>could now easily let it mean "flush the I-cache".  Good idea?

...but the 1.3B arch/mac68k/mac68k/trap.c has

/*      $NetBSD: trap.c,v 1.55 1997/11/07 07:33:15 scottr Exp $ */

[...]

        /*
         * Trace traps.
         *
         * M68k NetBSD uses trap #2,
         * SUN 3.x uses trap #15,
         * KGDB uses trap #15 (for kernel breakpoints; handled elsewhere).
         *
         * M68k NetBSD traps get mapped by locore.s into T_TRACE.
         * SUN 3.x traps get passed through as T_TRAP15 and are not really
         * supported yet.
         */
        case T_TRACE:           /* Kernel trace trap */
        case T_TRAP15:          /* SUN trace trap */

[...]

        case T_TRACE|T_USER:    /* user trace trap */
        case T_TRAP15|T_USER:   /* Sun user trace trap */
#ifdef COMPAT_SUNOS
                /*
                 * SunOS uses Trap #2 for a "CPU cache flush"
                 * Just flush the on-chip caches and return.
                 * XXX - Too bad NetBSD uses trap 2...
                 */


>Again, gcc could just do "trap #2" on both SunOS and NetBSD...
>
>Gordon

- ???

	hauke


--
"It's never straight up and down"     (DEVO)