Re: [Qemu-devel] [PATCH for-2.3] powerpc: fix -machine usb=no for newworld and pseries machines

[Alexander Graf <agraf@suse.de>]

On 03/23/2015 07:20 PM, Marcel Apfelbaum wrote:
> On 03/23/2015 07:05 PM, Paolo Bonzini wrote:
>> Capture the explicit setting of "usb=no" into a separate bool, and
>> use it to skip the update of machine->usb in the board init function.
>>
>> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
>> ---
>>   hw/core/machine.c     | 1 +
>>   hw/ppc/mac_newworld.c | 2 +-
>>   hw/ppc/spapr.c        | 2 +-
>>   include/hw/boards.h   | 1 +
>>   4 files changed, 4 insertions(+), 2 deletions(-)
>>
>> diff --git a/hw/core/machine.c b/hw/core/machine.c
>> index cb1185a..25c45e6 100644
>> --- a/hw/core/machine.c
>> +++ b/hw/core/machine.c
>> @@ -223,6 +223,7 @@ static void machine_set_usb(Object *obj, bool 
>> value, Error **errp)
>>       MachineState *ms = MACHINE(obj);
>>
>>       ms->usb = value;
>> +    ms->usb_disabled = !value;
> Maybe is too late now, but I really not like this pollution of 
> MachineState
> with 'usb_disabled'. (Imagine we have this kind of fields for lots of 
> objects and lots
> of corner cases...)
> I know it comes to solve a bug, but we talked about it in another mail 
> thread and
> this change in semantics was approved.
>
> Let me explain *why* I don't like it.
> 1. We add an "usb_disabled" field to a base class (actually object)
>    of all the machines and the only place it is interesting is
>    for 2 machines on ppc.
> 2. Even for these 2 machines, the scenario of defaults=on and usb=off
>    is not practical.

I'm personally fine either way, but I assumed that Paolo had a good 
reason for writing the patch?


Alex