Re: [Qemu-devel] [PATCH v2 16/45] scsi-disk: Track tray locked state

[Markus Armbruster]

Hannes Reinecke <address@hidden> writes:

> On 08/03/2011 03:07 PM, Markus Armbruster wrote:
>> We already track it in BlockDriverState.  Just like tray open/close
>> state, we should track it in the device models instead, because it's
>> device state.
>>
>> Signed-off-by: Markus Armbruster<address@hidden>
>> ---
>>   hw/scsi-disk.c |    4 +++-
>>   1 files changed, 3 insertions(+), 1 deletions(-)
>>
>> diff --git a/hw/scsi-disk.c b/hw/scsi-disk.c
>> index db72b86..8ca69f2 100644
>> --- a/hw/scsi-disk.c
>> +++ b/hw/scsi-disk.c
>> @@ -73,6 +73,7 @@ struct SCSIDiskState
>>       char *serial;
>>       SCSISense sense;
>>       bool tray_open;
>> +    bool tray_locked;
>>   };
>>
> Hmm. Shouldn't we use a more generic 'flags' here and have bits for
> the individual tray states?
> Feels like a waste to have individual values here.

On my system, struct SCSIDiskState is 248 bytes before my series (5
bytes of padding at the end), and 248 bytes after (3 bytes padding).  We
use one per disk.

I dare say switching to flags won't make a noticable difference in
memory use ;)

The bool members are easy to read and hard to screw up.

Flags can be nicer when you manipulate several of them together.