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ac131313@cygnus.com said: > I'm slightly curious about what is going on with all these different > breakpoints (I should hasten to point out that I'm _not_ the ARM > expert/maintainer :-). Stan Shebs recently commited the change: > 1999-03-02 Stan Shebs <shebs@andros.cygnus.com> > From Gary Thomas <gthomas@cygnus.co.uk>: > * arm-tdep.c (ARM_LE_BREAKPOINT, ARM_BE_BREAKPOINT, > THUMB_LE_BREAKPOINT, THUMB_BE_BREAKPOINT): Use illegal instruction > instead of SWI 24. > * config/arm/tm-arm.h (CALL_DUMMY): Ditto. > (IN_SIGTRAMP): Define. A bit of history. SWI 24 was the breakpoint swi in RISC iX, which the kernel understood (in some way). I don't know if it was necessary to use exactly that SWI if you were using gdb or if the same effect could be achieved with other illegal instructions. A side-note, before ARM Architecture v4 many "undefined" instruction formats aren't guaranteed to take the undefined instruction trap. Also note that, in this respect, the ARM7TDMI is NOT fully ARM v4 compliant. I don't know if anyone cares about RISC iX support any more (though gcc still supports it). Richard.