On Fri, 22 Dec 2017 11:47:00 -0800 Alistair Francis <alistair.fran...@xilinx.com> wrote:
> On Fri, Dec 22, 2017 at 10:45 AM, Alistair Francis > <alistair.fran...@xilinx.com> wrote: > > On Wed, Dec 20, 2017 at 2:06 PM, Eduardo Habkost <ehabk...@redhat.com> > > wrote: > >> On Tue, Dec 19, 2017 at 05:03:59PM -0800, Alistair Francis wrote: > >>> On Tue, Dec 19, 2017 at 4:55 PM, Alistair Francis > >>> <alistair.fran...@xilinx.com> wrote: > >>> > On Tue, Dec 19, 2017 at 4:43 PM, Peter Maydell > >>> > <peter.mayd...@linaro.org> wrote: > >>> >> On 20 December 2017 at 00:27, Alistair Francis > >>> >> <alistair.fran...@xilinx.com> wrote: > >>> >>> There are numorous QEMU machines that only have a single or a handful > >>> >>> of > >>> >>> valid CPU options. To simplyfy the management of specificying which > >>> >>> CPU > >>> >>> is/isn't valid let's create a property that can be set in the machine > >>> >>> init. We can then check to see if the user supplied CPU is in that > >>> >>> list > >>> >>> or not. > >>> >>> > >>> >>> I have added the valid_cpu_types for some ARM machines only at the > >>> >>> moment. > >>> >>> > >>> >>> Here is what specifying the CPUs looks like now: > >>> >>> > >>> >>> $ aarch64-softmmu/qemu-system-aarch64 -M netduino2 -kernel > >>> >>> ./u-boot.elf -nographic -cpu "cortex-m3" -S > >>> >>> QEMU 2.10.50 monitor - type 'help' for more information > >>> >>> (qemu) info cpus > >>> >>> * CPU #0: thread_id=24175 > >>> >>> (qemu) q > >>> >>> > >>> >>> $ aarch64-softmmu/qemu-system-aarch64 -M netduino2 -kernel > >>> >>> ./u-boot.elf -nographic -cpu "cortex-m4" -S > >>> >>> QEMU 2.10.50 monitor - type 'help' for more information > >>> >>> (qemu) q > >>> >>> > >>> >>> $ aarch64-softmmu/qemu-system-aarch64 -M netduino2 -kernel > >>> >>> ./u-boot.elf -nographic -cpu "cortex-m5" -S > >>> >>> qemu-system-aarch64: unable to find CPU model 'cortex-m5' > >>> >>> > >>> >>> $ aarch64-softmmu/qemu-system-aarch64 -M netduino2 -kernel > >>> >>> ./u-boot.elf -nographic -cpu "cortex-a9" -S > >>> >>> qemu-system-aarch64: Invalid CPU type: cortex-a9-arm-cpu > >>> >>> The valid types are: cortex-m3-arm-cpu, cortex-m4-arm-cpu > >>> >> > >>> >> Thanks for this; we really should be more strict about > >>> >> forbidding "won't work" combinations than we have > >>> >> been in the past. > >>> >> > >>> >> In the last of these cases, I think that when we > >>> >> list the invalid CPU type and the valid types > >>> >> we should use the same names we want the user to > >>> >> use on the command line, without the "-arm-cpu" > >>> >> suffixes. > >>> > > >>> > Hmm... That is a good point, it is confusing that they don't line up. > >> > >> Agreed. > >> > >>> > > >>> > The problem is that we are just doing a simple > >>> > object_class_dynamic_cast() in hw/core/machine.c which I think > >>> > (untested) requires us to have the full name in the valid cpu array. > >> [...] > >>> > >>> I think an earlier version of my previous series adding the support to > >>> machine.c did string comparison, but it was decided to utilise objects > >>> instead. One option is to make the array 2 wide and have the second > >>> string be user friendly? > >> > >> Making the array 2-column will duplicate information that we can > >> already find out using other methods, and it won't solve the > >> problem if an entry has a parent class with multiple subclasses > >> (the original reason I suggested object_class_dynamic_cast()). > >> > >> The main obstacle to fix this easily is that we do have a common > >> ObjectClass *cpu_class_by_name(const char *cpu_model) > >> function, but not a common method to get the model name from a > >> CPUClass. Implementing this is possible, but probably better to > >> do it after moving the existing arch-specific CPU model > >> enumeration hooks to common code (currently we duplicate lots of > >> CPU enumeration/lookup boilerplate code that we shouldn't have > >> to). > >> > >> Listing only the human-friendly names in the array like in the > >> original patch could be a reasonable temporary solution. It > >> won't allow us to use a single entry for all subclasses of a > >> given type by now (e.g. listing only TYPE_X86_CPU on PC), but at > >> least we can address this issue without waiting for a refactor of > >> the CPU model enumeration code. > > Ah, I just re-read this. Do you mean go back to the original RFC and > just use strcmp() to compare the human readable cpu_model? It's sort of going backwards but I won't object to this as far as you won't use machine->cpu_model (which is in process of being removed) BTW: how hard is it, to add cpu_type2cpu_name function? > Alistair > > > > > Ok, so it sounds like I'll respin this series with an extra column in > > the array for human readable names. Then in the future we can work on > > removing that. > > > > Alistair > > > >> > >> -- > >> Eduardo > >>
