From mboxrd@z Thu Jan 1 00:00:00 1970 From: Richard Earnshaw To: gdb-patches@cygnus.com Cc: richard.earnshaw@arm.com Subject: Re: support for ARM GNU/Linux Date: Wed, 14 Apr 1999 03:36:00 -0000 Message-id: <199904140952.KAA25068@sun52.NIS.cambridge> References: <37142B16.B43B5200@cygnus.com> X-SW-Source: 1999-04/msg00026.html 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 > From Gary Thomas : > * 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. From mboxrd@z Thu Jan 1 00:00:00 1970 From: Richard Earnshaw To: gdb-patches@cygnus.com Cc: richard.earnshaw@arm.com Subject: Re: support for ARM GNU/Linux Date: Wed, 14 Apr 1999 02:52:00 -0000 Message-ID: <199904140952.KAA25068@sun52.NIS.cambridge> References: <37142B16.B43B5200@cygnus.com> X-SW-Source: 1999-q2/msg00026.html Message-ID: <19990414025200.eflnMvOLVlZ3_XFmwd1LIE8vcgmJTbhik5WHglGzVAQ@z> 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 > From Gary Thomas : > * 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.