Re: [PATCH for-5.1 2/2] tpm: Improve help on TPM types when none are available

[Stefan Berger <stefanb@linux.ibm.com>]

On 7/23/20 8:49 AM, Philippe Mathieu-Daudé wrote:
> On 7/23/20 1:58 PM, Markus Armbruster wrote:
>> Help is a bit awkward when no TPM types are built into QEMU:
>>
>>      $ upstream-qemu -tpmdev nonexistent,id=tpm0
>>      upstream-qemu: -tpmdev nonexistent,id=tpm0: Parameter 'type' expects a TPM backend type
>>      Supported TPM types (choose only one):
>>
>> Improve to
>>
>>      upstream-qemu: -tpmdev nonexistent,id=tpm0: Parameter 'type' expects a TPM backend type
>>      No TPM backend types are available
>>
>> Signed-off-by: Markus Armbruster <armbru@redhat.com>
> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>


Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>


>
>> ---
>>   tpm.c | 13 +++++++++----
>>   1 file changed, 9 insertions(+), 4 deletions(-)
>>
>> diff --git a/tpm.c b/tpm.c
>> index f6045bb6da..cab206355a 100644
>> --- a/tpm.c
>> +++ b/tpm.c
>> @@ -47,18 +47,23 @@ tpm_be_find_by_type(enum TpmType type)
>>    */
>>   static void tpm_display_backend_drivers(void)
>>   {
>> +    bool got_one = false;
>>       int i;
>>   
>> -    fprintf(stderr, "Supported TPM types (choose only one):\n");
>> -
>>       for (i = 0; i < TPM_TYPE__MAX; i++) {
>>           const TPMBackendClass *bc = tpm_be_find_by_type(i);
>>           if (!bc) {
>>               continue;
>>           }
>> -        fprintf(stderr, "%12s   %s\n", TpmType_str(i), bc->desc);
>> +        if (!got_one) {
>> +            error_printf("Supported TPM types (choose only one):\n");
>> +            got_one = true;
>> +        }
>> +        error_printf("%12s   %s\n", TpmType_str(i), bc->desc);
>> +    }
>> +    if (!got_one) {
>> +        error_printf("No TPM backend types are available\n");
>>       }
>> -    fprintf(stderr, "\n");
>>   }
>>   
>>   /*
>>