On Tue, 5 Sep 2017 10:08:01 +0100 Peter Maydell <peter.mayd...@linaro.org> wrote:
> On 4 September 2017 at 20:38, Igor Mammedov <imamm...@redhat.com> wrote: > > On Mon, 4 Sep 2017 17:36:59 +0100 > > Peter Maydell <peter.mayd...@linaro.org> wrote: > > > >> I just got bitten by qdev_get_machine()'s behaviour on the user-only > >> emulators, where it can return something that isn't NULL and isn't > >> an instance of TYPE_MACHINE either. > > user-only shouldn't get to qdev_get_machine() at all, > > issue probably in container_get(). > > I need it in cpu_common_realizefn(), for > http://patchwork.ozlabs.org/patch/797940/ Link might be broken (unable to connect to server) Anyways I'd avoid using machine from cpu_*_realizefn(), instead of I'd add property to CPU that has needed data and set it from board code. Should work fine for *-user targets and maintain clear separation of device impl. and board details. > > > I'd try to fix wrong user if possible and maybe add ifdef build failure > > to qdev_get_machine() so it would not build in user mode. > > Can't ifdef, that source file is built once for all targets. > > My fix (which I intend to send to the list today) is to make > it do the object_dynamic_cast() check -- if that doesn't give > a TYPE_MACHINE then we're in user mode and don't need to set > ignore_memory_transaction_failures on the cpu object anyway. > > >> It looks like maybe this can happen in some cases in softmmu too, > >> judging by the way that qdev_get_hotplug_handler() does an > >> object_dynamic_cast() check that it really got back a TYPE_MACHINE. > > As I recall only bus or machine provide hotplug_handler currently, > > but it's possible to extend to other objects if we find use-case. > > > > We could do static cast to machine instead dynamic there but > > in hotplug case it will abort QEMU if error happens, > > hence dynamic check to avoid be more resilient during hotplug. > > (well, if qdev_get_machine() returns not machine during startup > > we would be screwed anyways, but that should break much earlier) > > If this can't ever happen then we should be aborting; that's > the idea behind the cast macros doing assertions. I'm not > sure hotplug needs to be special here if it doesn't have > a genuine reason to think it might get back something of > the wrong type. Yep, we should abort. > > thanks > -- PMM
