Peter Maydell <peter.mayd...@linaro.org> writes:
> On Fri, 4 Feb 2022 at 09:28, Alex Bennée <alex.ben...@linaro.org> wrote: >> Assuming you are happy for the device to act as though a external >> debugger is attached regardless of the gdbstub state you could use a CPU >> property on the command line to enable this behaviour. We have some >> examples for SVE for the 64 bit CPUs (see object_property_add for >> sve-max-vq). So something like: >> >> -cpu cortex-m3,dhscr=true >> >> You would probably want to model the behaviour of DHSCR.C_HALT as well >> because that is something the core might do to itself if it detects it >> is running under debug. > > This is sounding pretty hacky to me. I think we should either have > a proper implementation of all of halting debug (probably opt-in, > with the default being that the gdbstub is transparent to the guest), So we could flip it and make it a property of gdbstub with transparency being the default. Then any architecture that wanted to have this behaviour could query the stub if enabled. > or we should just say that no, this isn't something we support, > and if you want gdb to get control when a particular bit of code > is executed then you should set a breakpoint there. It's a fairly niche use case but I don't see why we shouldn't assuming someone is willing to write the code. However I suspect there is quite a wide range of potential behaviours to model. > We don't even implement the guest-visible debug parts of the > architecture (eg architected single-step) yet, incidentally. Is this just for Aarch32? Because for Aarch64 as far as I'm aware the v8.0 debug works fine modulo bugs which I sent a fix for: Subject: [RFC PATCH] arm: force flag recalculation when messing with DAIF Date: Wed, 2 Feb 2022 12:23:53 +0000 Message-Id: <20220202122353.457084-1-alex.ben...@linaro.org> Implementing more of the debug functionality is on the list for supporting Neoverse. We don't currently have a plan for how to deal with the slowly growing series of PMU features though. > > -- PMM -- Alex Bennée
