Got it. Sent from my cell phone, please ignore typos
On Mon, Jun 3, 2019, 7:37 PM Richard Henderson <richard.hender...@linaro.org> wrote: > On 6/3/19 11:29 AM, Michael Rolnik wrote: > > 1. There's a break > > instruction > https://www.microchip.com/webdoc/avrassembler/avrassembler.wb_BREAK.html > > 2. There's a set of tests that use break. > > > > So I assume I have to implement this instruction as described in the > spec. > > The spec talks about fuses, not gdb. A valid implementation of this > instruction is a no-op -- it say so right there in the spec. > > What does it mean to "test" break? AFAIK, you can't test this at all from > within the cpu itself, since it does not generate a cpu-level exception. > > If gdb is setting a breakpoint via -S, it should be done via > cpu_breakpoint_test. > > > > > On Mon, Jun 3, 2019, 6:44 PM Richard Henderson < > richard.hender...@linaro.org > > <mailto:richard.hender...@linaro.org>> wrote: > > > > On 6/1/19 4:12 PM, Michael Rolnik wrote: > > > Hi Richard. > > > > > > If I implement it this way > > > > > > ``` > > > static bool trans_BREAK(DisasContext *ctx, arg_BREAK *a) > > > { > > > if (avr_feature(ctx->env, AVR_FEATURE_BREAK) == false) { > > > gen_helper_unsupported(cpu_env); > > > } else { > > > tcg_gen_movi_tl(cpu_pc, ctx->inst[0].npc); > > > gen_helper_debug(cpu_env); > > > } > > > > > > ctx->bstate = BS_EXCP; > > > > > > return true; > > > } > > > ``` > > > > > > qemu (without -s -S flags) crashes when debugger is not connected > > > > I was not suggesting using the internal qemu EXCP_DEBUG, but another > AVR > > specific exception, much the same way as every other cpu has a > cpu-specific > > debug exception. > > > > Or perhaps always do nothing. Why is gdb insertting BREAK in the > first place? > > It should be using the "hardware breakpoint" support that qemu > advertises as > > part of the gdbstub protocol, and that you support here: > > > > > + if (unlikely(cpu_breakpoint_test(cs, OFFSET_CODE + cpc * > 2, BP_ANY)) > > > + || cpu_breakpoint_test(cs, OFFSET_DATA + cpc * 2, > > BP_ANY)) { > > > + tcg_gen_movi_i32(cpu_pc, cpc); > > > + gen_helper_debug(cpu_env); > > > + ctx.bstate = BS_EXCP; > > > + goto done_generating; > > > + } > >
