On Mon, 17 Jun 2019 17:15:21 +0200 Philippe Mathieu-Daudé <phi...@redhat.com> wrote:
> On 6/17/19 5:01 PM, Igor Mammedov wrote: > > On Mon, 17 Jun 2019 07:09:59 +0200 > > Philippe Mathieu-Daudé <phi...@redhat.com> wrote: > > > >> Hi Igor, Eduardo, > >> > >> On 2/6/18 3:43 PM, Igor Mammedov wrote: > >>> On Mon, 5 Feb 2018 20:42:05 -0200 > >>> Eduardo Habkost <ehabk...@redhat.com> wrote: > >>> > >>>> On Mon, Feb 05, 2018 at 03:42:02PM +0100, Igor Mammedov wrote: > >>>>> On Mon, 5 Feb 2018 11:54:01 -0200 > >>>>> Eduardo Habkost <ehabk...@redhat.com> wrote: > >>>>> > >>>>>> On Mon, Feb 05, 2018 at 12:22:35PM +0100, Igor Mammedov wrote: > >>>>>>> On Fri, 2 Feb 2018 16:23:26 -0200 > >>>>>>> Eduardo Habkost <ehabk...@redhat.com> wrote: > >>>>>>> > >>>>>>>> On Thu, Feb 01, 2018 at 04:42:05PM -0800, Alistair Francis wrote: > >>>>>>>> > >>>>>>>>> As cpu_type is not a user visible string let's convert the > >>>>>>>>> valid_cpu_types to compare against cpu_model instead. This way we > >>>>>>>>> have a > >>>>>>>>> user friendly string to report back. > >>>>>>>>> > >>>>>>>>> Once we have a cpu_type to cpu_model conversion this patch should be > >>>>>>>>> reverted and we should use cpu_type instead. > >>>>>>>>> > >>>>>>>>> Signed-off-by: Alistair Francis <alistair.fran...@xilinx.com> > >>>>>>>>> --- > >>>>>>>>> > >>>>>>>>> hw/core/machine.c | 11 +++++------ > >>>>>>>>> 1 file changed, 5 insertions(+), 6 deletions(-) > >>>>>>>>> > >>>>>>>>> diff --git a/hw/core/machine.c b/hw/core/machine.c > >>>>>>>>> index cdc1163dc6..de5bac1c84 100644 > >>>>>>>>> --- a/hw/core/machine.c > >>>>>>>>> +++ b/hw/core/machine.c > >>>>>>>>> @@ -776,13 +776,12 @@ void machine_run_board_init(MachineState > >>>>>>>>> *machine) > >>>>>>>>> /* If the machine supports the valid_cpu_types check and the > >>>>>>>>> user > >>>>>>>>> * specified a CPU with -cpu check here that the user CPU is > >>>>>>>>> supported. > >>>>>>>>> */ > >>>>>>>>> - if (machine_class->valid_cpu_types && machine->cpu_type) { > >>>>>>>>> - ObjectClass *class = > >>>>>>>>> object_class_by_name(machine->cpu_type); > >>>>>>>>> + if (machine_class->valid_cpu_types && machine->cpu_model) { > >>>>>>>>> int i; > >>>>>>>>> > >>>>>>>>> for (i = 0; machine_class->valid_cpu_types[i]; i++) { > >>>>>>>>> - if (object_class_dynamic_cast(class, > >>>>>>>>> - > >>>>>>>>> machine_class->valid_cpu_types[i])) { > >>>>>>>>> + if (!strcmp(machine->cpu_model, > >>>>>>>>> + machine_class->valid_cpu_types[i])) { > >>>>>>>>> > >>>>>>>> > >>>>>>>> I would rename valid_cpu_types to valid_cpu_models to make the > >>>>>>>> new semantics clearer. > >>>>>>>> > >>>>>>>> Anyway, I have bad and good news: > >>>>>>>> > >>>>>>>> The bad news is Igor already sent patches last week that remove > >>>>>>>> MachineState::cpu_model, so this conflicts with his series. Now > >>>>>>>> parse_cpu_model() will be the only place where the original CPU > >>>>>>>> model name is > >>>>>>>> available, but the function needs to work on *-user too. See: > >>>>>>>> "[PATCH v3 23/25] Use cpu_create(type) instead of > >>>>>>>> cpu_init(cpu_model)". > >>>>>>>> > >>>>>>>> The good news is that I think we can fix this very easily if > >>>>>>>> validation is done at the same place where parse_cpu_model() is > >>>>>>>> called. e.g.: > >>>>>>>> > >>>>>>>> current_machine->cpu_type = machine_class->default_cpu_type; > >>>>>>>> if (cpu_model) { > >>>>>>>> current_machine->cpu_type = parse_cpu_model(cpu_model); > >>>>>>>> > >>>>>>>> if (machine_class->valid_cpu_models) { > >>>>>>>> ObjectClass *class = > >>>>>>>> object_class_by_name(machine->cpu_type); > >>>>>>>> int i; > >>>>>>>> > >>>>>>>> for (i = 0; machine_class->valid_cpu_models[i]; i++) { > >>>>>>>> const char *valid_model = > >>>>>>>> machine_class->valid_cpu_models[i]; > >>>>>>>> ObjectClass *valid_class = > >>>>>>>> cpu_class_by_name(machine->cpu_type, valid_model); > >>>>>>>> if (object_class_dynamic_cast(class, > >>>>>>>> > >>>>>>>> object_class_get_name(valid_class))) { > >>>>>>>> /* Valid CPU type, we're good to go */ > >>>>>>>> break; > >>>>>>>> } > >>>>>>>> } > >>>>>>>> if (!machine_class->valid_cpu_models[i]) { > >>>>>>>> error_report("Invalid CPU model: %s", cpu_model); > >>>>>>>> error_printf("The valid CPU models are: %s", > >>>>>>>> machine_class->valid_cpu_models[0]); > >>>>>>>> for (i = 1; machine_class->valid_cpu_models[i]; i++) > >>>>>>>> { > >>>>>>>> error_printf(", %s", > >>>>>>>> machine_class->valid_cpu_models[i]); > >>>>>>>> } > >>>>>>>> error_printf("\n"); > >>>>>>>> exit(1); > >>>>>>>> } > >>>>>>>> } > >>>>>>>> } > >>>>>>>> > >>>>>>>> This can be done inside main(), or moved inside > >>>>>>>> machine_run_board_init() if main() pass cpu_model as argument to > >>>>>>>> the function. > >>>>>>>> > >>>>>>>> On either case, I think it's a good idea to do validation and > >>>>>>>> printing of error messages closer to the code that parses the > >>>>>>>> command-line options. This way we separate parsing/validation > >>>>>>>> from initialization. > >>>>>>> I agree it's better like you suggest as at least it prevents > >>>>>>> ms->cpu_model creeping back into boards code. > >>>>>>> > >>>>>>> But I still dislike (hate) an idea of new code adding non > >>>>>>> canonized cpu_model strings back in the boards code. > >>>>>>> It's just a matter of time when someone would use them > >>>>>>> and cpu_model parsing will creep back into boards. > >>>>>>> > >>>>>>> It would be much better to if we add > >>>>>>> char *MachineClass::cpu_name_by_type_name(char *cpu_type) > >>>>>>> callback and let machines in this patchset to set it, > >>>>>>> something along following lines which is not much of > >>>>>>> refactoring and allows for gradual conversion: > >>>>>>> > >>>>>>> diff --git a/target/arm/cpu.h b/target/arm/cpu.h > >>>>>>> index 9631670..85cca84 100644 > >>>>>>> --- a/target/arm/cpu.h > >>>>>>> +++ b/target/arm/cpu.h > >>>>>>> @@ -2885,4 +2885,6 @@ static inline void > >>>>>>> *arm_get_el_change_hook_opaque(ARMCPU *cpu) > >>>>>>> return cpu->el_change_hook_opaque; > >>>>>>> } > >>>>>>> > >>>>>>> +char *arm_cpu_name_by_type_name(const char *typename); > >>>>>>> + > >>>>>>> #endif > >>>>>>> diff --git a/hw/arm/netduino2.c b/hw/arm/netduino2.c > >>>>>>> index f936017..ae6adb7 100644 > >>>>>>> --- a/hw/arm/netduino2.c > >>>>>>> +++ b/hw/arm/netduino2.c > >>>>>>> @@ -46,6 +46,7 @@ static void netduino2_machine_init(MachineClass *mc) > >>>>>>> mc->desc = "Netduino 2 Machine"; > >>>>>>> mc->init = netduino2_init; > >>>>>>> mc->ignore_memory_transaction_failures = true; > >>>>>>> + mc->cpu_name_by_type_name = arm_cpu_name_by_type_name: > >>>>>> > >>>>>> I really don't want to introduce a new arch-specific hook just > >>>>>> for that. We should move CPU type lookup logic to common code > >>>>>> and make it unnecessary to write new hooks. > >>>>> unfortunately cpu_model (cpu name part) is target specific > >>>>> and it's translation to type and back is target specific mayhem. > >>>> > >>>> Why can't the model<->type translation be represented as data? > >>>> We could have simple cpu_type_name_suffix + an alias table. > >>>> > >>>> We have at least 4 arches that return a constant at > >>>> class_by_name. We have at least 10 arches that simply add a > >>>> suffix to the CPU model name. We must make them use common code > >>>> instead of requiring them to implement yet another hook[1]. > >>> True, some of them could use generic hook and reduce > >>> code duplication greatly, we should do it regardless of whether > >>> table or target specific func approach is used. > >>> > >>>> In addition to the ones above, we have 3 that seem to just need > >>>> an alias table (cris, superh, alpha). ppc can probably also use > >>>> an alias table for the ppc_cpu_class_by_pvr() stuff. sparc just > >>>> needs whitespaces translated to '-' (sparc), which can be done > >>>> using an alias table. > >>>> > >>>> In the end I couldn't find any example that can't be represented > >>>> by a suffix + alias table. > >>> > >>> Table based approach is possible but it won't be as simple > >>> as you've just pictured it. > >>> > >>> From what I recall from cpu_class_by_name cleanups table should be able > >>> to describe cases like (sometimes combination of them): > >>> * 1:1 mapping - where cpu_model == cpu_type > >>> * cpu_model <==> cpu_model + suffix - most common usecase > >>> * cpu_model <==> prefix cpu_model - riscv patches on list are trying > >>> to add such cpu types > >>> * NULL => some_fixed type > >>> * case (in) sensitive flag > >>> * garbage => some_fixed type > >>> * substitutions > >>> * aliases (sometimes dynamic depending on --enable-kvm (PPC)) > >>> Maybe something else. > >>> > >>> We can think about it at leisure but I can't say if new approach > >>> complexity it's worth of the effort. > >>> > >>> It would be nice see impl, but it's a lot of refactoring that's > >>> clearly out of scope of this series. > >>> I'd prefer small incremental refactoring (if possible) that > >>> won't scare people of and easy to review vs a huge one. > >>> > >>>>> So I'd prefer having both back and forth functions together in > >>>>> one place. And common code to call them when necessary. > >>>>> > >>>>> We could do global cpu_name_by_type_name() instead of hook, > >>>>> which I'd prefer even more but then conversion can't be done > >>>>> only for one target but rather for all targets at once. > >>>> > >>>> I don't mind letting a few targets override default behavior with > >>>> a hook if really necessary, but I have a problem with requiring > >>>> all targets to implement what's basically the same boilerplate > >>>> code to add/remove a string suffix and translating aliases. > >>> it could be generic helper if target does the same plus > >>> not mandatory at that (in case target/board doesn't care > >>> about valid cpus). > >>> > >>>>>> I agree it would be better if we had a cpu_name_by_type_name() > >>>>>> function, but I would like to have it implemented cleanly. > >>>>> In some cases(targets) it can be common helper, but in other > >>>>> cases it's not so. > >>>>> My suggestion though allows to do gradual conversion and > >>>>> avoid putting cpu_model names back in board's code (which I just manged > >>>>> to remove). > >>>>> Once all targets converted and relevant code is isolated > >>>>> we can attempt to generalize it if it's possible or at least > >>>>> make of it global per target helper to get rid of > >>>>> temporary machine hook. > >>>>> > >>>>> (seeing this series reposted with cpu_model names in boards code, > >>>>> it doesn't looks like author would like to implement tree-wide > >>>>> generalization first) > >>>> > >>>> Well, if nobody is willing to generalize all target-specific code > >>>> right now, I don't see the harm in having cpu_model-based tables > >>>> in a few boards in the meantime (as this patch series does). But > >>>> I do see harm in requiring all our 20 targets to implement yet > >>>> another hook and increasing the costs of cleaning up the mess > >>>> later. > >>> If we use MachineClass hook then it might be done per target > >>> on demand, so no one would require that every target should > >>> implement it. > >>> Also there could be a generic helper for targets that do the same. > >>> Machine which needs to enable valid_cpus, will have to use generic > >>> hook impl or provide target specific if it's special case. > >>> > >>> Though I do see harm in adding cpu_model tables in boards code > >>> vs target specific hooks on demand as that will be copy-pasted > >>> in other boards afterwards (number of which is bigger compared > >>> to targets count) and ultimately it would duplicate cpu_name > >>> strings in every board vs hook approach where cpu_model could > >>> be calculated from cpu_type by a function (generic or > >>> target specific). > >>> > >>> Good thing about hook is that it's non intrusive and > >>> isolates(consolidates) existing cpu_type -> cpu_model > >>> conversion in multiple places into one place. > >>> Then later it would be easier to generalize if someone > >>> decides to do it. > >> > >> I wonder how you want to proceed with this series, the first patch got > >> merged (c9cf636d48f) but after your "CPU model name" rework, this commit > >> seems now not very complete/usable. > >> > >> Rebasing this series, i.e. with this snippet: > >> > >> -- >8 -- > >> diff --git a/hw/arm/netduino2.c b/hw/arm/netduino2.c > >> index f57fc38f92..cca4ec6648 100644 > >> --- a/hw/arm/netduino2.c > >> +++ b/hw/arm/netduino2.c > >> @@ -34,7 +34,7 @@ static void netduino2_init(MachineState *machine) > >> DeviceState *dev; > >> > >> dev = qdev_create(NULL, TYPE_STM32F205_SOC); > >> - qdev_prop_set_string(dev, "cpu-type", ARM_CPU_TYPE_NAME("cortex-m3")); > >> + qdev_prop_set_string(dev, "cpu-type", machine->cpu_type); > >> object_property_set_bool(OBJECT(dev), true, "realized", &error_fatal); > >> > >> armv7m_load_kernel(ARM_CPU(first_cpu), machine->kernel_filename, > >> @@ -43,8 +43,14 @@ static void netduino2_init(MachineState *machine) > >> > >> static void netduino2_machine_init(MachineClass *mc) > >> { > >> + static const char *valid_cpus[] = { > >> + ARM_CPU_TYPE_NAME("cortex-m3"), > >> + ARM_CPU_TYPE_NAME("cortex-m4"), > >> + NULL > >> + }; > >> mc->desc = "Netduino 2 Machine"; > >> mc->init = netduino2_init; > >> + mc->valid_cpu_types = valid_cpus; > >> mc->ignore_memory_transaction_failures = true; > >> } > >> --- > >> > >> We get cpu names with suffix: > >> > >> $ arm-softmmu/qemu-system-arm -M netduino2 -cpu arm926 > >> qemu-system-arm: Invalid CPU type: arm926-arm-cpu > >> The valid types are: cortex-m3-arm-cpu, cortex-m4-arm-cpu > >> > >> I understand you won't want a global cpu_name_by_type_name, how do you > >> want to do then? > >> > >> Should we define an automatically expanded TARGET_CPU_TYPE_SUFFIX? > >> Then we could have generic machine code to parse the names. > > It would work only for some cases, > > problem is that we have a zoo of naming schemes. > > Considering that cpus models are used widely we probably can't > > deprecate it outright (for versioned machine types). > > > > Instead of wasting resources on translating cpu-type => 'cpu-name', > > (hook or lookup tables) how about simplifying code and making all > > boards accept full typenames? > > > > It could be handled in generic way and then printing error with > > full type names would be acceptable since user would be able to feed it > > to -cpu. > > > > '-cpu help' - would need some work to display types as well (also could be > > generic) > > > > Perhaps with it we could deprecate cpu_models for non versioned > > machines/targets, which in most cases would allow us to drop special > > suffix/prefix/nonsense/case-sensitive/substitutions and whatever else > > is already existing and keep exiting translation routines (hooks) only > > for versioned machine types as necessary evil. Maybe we don't even need to keep it versioned machine types, considering change mapping is static and doesn't influence ABI/migration. Management interface could just translate cpu_model to type name for new QEMU. That would allow us to remove quite a bit target specific code that deals with all permutations of CPU model and replace a bunch of '-cpu help' target specific handlers with a generic enumeration of built-in CPU types. > Yes. Eduardo and you should write some lines to explain this, and then > we will follow :) Unfortunately I don't recall details anymore. One could check out all implementations of class_by_name callbacks to find out current state. > I feel concerned because: > 1/ Alistair series is very helpful to new users, and > 2/ As the RX architecture series showed, today it is not very clear how > to correctly use cpu_models. That's why I'm pushing for supporting only type names whenever possible so there won't be confusion anymore. Using types is consistent with -device and some QMP interfaces, enforces strict error checking so user would get error on nonsense input. > Eduardo is working on a series, I'll wait for his work. > > Regards, > > Phil.