Re: [PATCH 6/9] hw/arm/virt: Display list of valid CPUs for the Virt machine

[Philippe Mathieu-Daudé]

On 2/5/21 4:12 PM, Andrew Jones wrote:
> On Fri, Feb 05, 2021 at 03:43:42PM +0100, Philippe Mathieu-Daudé wrote:
>> The Virt machine is restricted to a subset of the CPU provided
>> by QEMU. Instead of having the user run '--cpu help' and try
>> each CPUs until finding a match, display the list from start:
>>
>>   $ qemu-system-aarch64 -M virt -cpu cortex-a8
>>   qemu-system-aarch64: mach-virt: CPU type cortex-a8 not supported
>>   qemu-system-aarch64: mach-virt: Please select one of the following CPU 
>> types:  cortex-a7, cortex-a15, cortex-a53, cortex-a57, cortex-a72, host, max
>>
>> Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
>> ---
>>  hw/arm/virt.c | 11 +++++++++++
>>  1 file changed, 11 insertions(+)
>>
>> diff --git a/hw/arm/virt.c b/hw/arm/virt.c
>> index 7802d3a66e8..6ffe091804f 100644
>> --- a/hw/arm/virt.c
>> +++ b/hw/arm/virt.c
>> @@ -1830,9 +1830,20 @@ static void machvirt_init(MachineState *machine)
>>  
>>      if (!cpu_type_valid(machine->cpu_type)) {
>>          int len = strlen(machine->cpu_type) - strlen(ARM_CPU_TYPE_SUFFIX);
>> +        g_autoptr(GString) s = g_string_new(NULL);
>>  
>>          error_report("mach-virt: CPU type %.*s not supported",
>>                       len, machine->cpu_type);
>> +
>> +        for (n = 0; n < ARRAY_SIZE(valid_cpus); n++) {
>> +            len = strlen(valid_cpus[n]) - strlen(ARM_CPU_TYPE_SUFFIX);
>> +            g_string_append_printf(s, " %.*s", len, valid_cpus[n]);
>> +            if (n + 1 < ARRAY_SIZE(valid_cpus)) {
>> +                g_string_append_c(s, ',');
>> +            }
>> +        }
>> +        error_report("mach-virt: Please select one of the following CPU 
>> types: %s",
>> +                     g_string_free(s, FALSE));
>>          exit(1);
>>      }
>>  
>> -- 
>> 2.26.2
>>
> 
> It'd be nice if './qemu-system-aarch64 -M virt -cpu \?' would only output
> the CPUs that the virt machine type supports. Then this error message
> could suggest running that in order to get the list.

+1 very nice =) But not how the command line options processing
works. Maybe later after John Snow command line rework is merged?