Re: [Qemu-devel] [PATCH 4/6] qapi: change the type of TargetInfo.arch from string to enum SysEmuTarget

[Laszlo Ersek <lersek@redhat.com>]

On 04/25/18 08:48, Markus Armbruster wrote:
> Laszlo Ersek <lersek@redhat.com> writes:
> 
>> Now that we have @SysEmuTarget, it makes sense to restict
>> @TargetInfo.@arch to valid sysemu targets at the schema level.
>>
>> Cc: "Daniel P. Berrange" <berrange@redhat.com>
>> Cc: David Gibson <dgibson@redhat.com>
>> Cc: Eric Blake <eblake@redhat.com>
>> Cc: Gerd Hoffmann <kraxel@redhat.com>
>> Cc: Kashyap Chamarthy <kchamart@redhat.com>
>> Cc: Markus Armbruster <armbru@redhat.com>
>> Cc: Paolo Bonzini <pbonzini@redhat.com>
>> Cc: Thomas Huth <thuth@redhat.com>
>> Signed-off-by: Laszlo Ersek <lersek@redhat.com>
>> ---
>>
>> Notes:
>>     PATCHv1:
>>     
>>     - qmp_query_target(): pass (-1) as fallback value [Markus]
>>     - qmp_query_target(): catch lookup error with error_abort [Markus]
>>     
>>     RFCv3:
>>     
>>     - The patch is new in this version. [Markus]
>>
>>  qapi/misc.json |  6 ++++--
>>  arch_init.c    | 10 +++++++++-
>>  2 files changed, 13 insertions(+), 3 deletions(-)
>>
>> diff --git a/qapi/misc.json b/qapi/misc.json
>> index 104d013adba6..460866cf542f 100644
>> --- a/qapi/misc.json
>> +++ b/qapi/misc.json
>> @@ -1,18 +1,20 @@
>>  # -*- Mode: Python -*-
>>  #
>>  
>>  ##
>>  # = Miscellanea
>>  ##
>>  
>> +{ 'include': 'common.json' }
>> +
>>  ##
>>  # @qmp_capabilities:
>>  #
>>  # Enable QMP capabilities.
>>  #
>>  # Arguments:
>>  #
>>  # @enable:   An optional list of QMPCapability values to enable.  The
>>  #            client must not enable any capability that is not
>>  #            mentioned in the QMP greeting message.  If the field is not
>>  #            provided, it means no QMP capabilities will be enabled.
>> @@ -2441,28 +2443,28 @@
>>  #      ]
>>  #    }
>>  #
>>  ##
>>  { 'command': 'query-fdsets', 'returns': ['FdsetInfo'] }
>>  
>>  ##
>>  # @TargetInfo:
>>  #
>>  # Information describing the QEMU target.
>>  #
>> -# @arch: the target architecture (eg "x86_64", "i386", etc)
>> +# @arch: the target architecture
>>  #
>>  # Since: 1.2.0
>>  ##
>>  { 'struct': 'TargetInfo',
>> -  'data': { 'arch': 'str' } }
>> +  'data': { 'arch': 'SysEmuTarget' } }
>>  
>>  ##
>>  # @query-target:
>>  #
>>  # Return information about the target for this QEMU
>>  #
>>  # Returns: TargetInfo
>>  #
>>  # Since: 1.2.0
>>  ##
>>  { 'command': 'query-target', 'returns': 'TargetInfo' }
>> diff --git a/arch_init.c b/arch_init.c
>> index 6ee07478bd11..ee3a57019000 100644
>> --- a/arch_init.c
>> +++ b/arch_init.c
>> @@ -21,22 +21,23 @@
>>   * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
>>   * THE SOFTWARE.
>>   */
>>  #include "qemu/osdep.h"
>>  #include "qemu-common.h"
>>  #include "cpu.h"
>>  #include "sysemu/sysemu.h"
>>  #include "sysemu/arch_init.h"
>>  #include "hw/pci/pci.h"
>>  #include "hw/audio/soundhw.h"
>>  #include "qapi/qapi-commands-misc.h"
>> +#include "qapi/error.h"
>>  #include "qemu/config-file.h"
>>  #include "qemu/error-report.h"
>>  #include "hw/acpi/acpi.h"
>>  #include "qemu/help_option.h"
>>  
>>  #ifdef TARGET_SPARC
>>  int graphic_width = 1024;
>>  int graphic_height = 768;
>>  int graphic_depth = 8;
>>  #else
>>  int graphic_width = 800;
>> @@ -104,15 +105,22 @@ int xen_available(void)
>>      return 1;
>>  #else
>>      return 0;
>>  #endif
>>  }
>>  
>>  
>>  TargetInfo *qmp_query_target(Error **errp)
>>  {
>>      TargetInfo *info = g_malloc0(sizeof(*info));
>>  
>> -    info->arch = g_strdup(TARGET_NAME);
>> +    /*
>> +     * The fallback enum value is irrelevant here (TARGET_NAME is a
>> +     * macro and can never be NULL), so simply pass (-1). Also, the
>> +     * lookup should never fail -- if it fails, then @SysEmuTarget needs
>> +     * extending. Catch that with "error_abort".
>> +     */
>> +    info->arch = qapi_enum_parse(&SysEmuTarget_lookup, TARGET_NAME, -1,
>> +                                 &error_abort);
>>  
>>      return info;
>>  }
> 
> Not sure the comment is carrying its weight; for me, the use of -1 and
> &error_abort feels obvious enough.  But my feelings are subjective and
> could be off.

No, you are right, I'll drop the comment. I had to explain the arguments
to myself at first, but in retrospect they're not complicated enough to
merit a comment.

> Reviewed-by: Markus Armbruster <armbru@redhat.com>
> 

Thanks!
Laszlo