Re: [Qemu-devel] [PATCH 15/20] acpi: switch smbus to memory api

[Gerd Hoffmann <kraxel@redhat.com>]

On 11/26/12 16:18, Andreas Färber wrote:
> Am 23.11.2012 16:48, schrieb Gerd Hoffmann:
>> diff --git a/hw/pm_smbus.c b/hw/pm_smbus.c
>> index 5d6046d..ea1380c 100644
>> --- a/hw/pm_smbus.c
>> +++ b/hw/pm_smbus.c
> [...]
>> @@ -170,7 +170,16 @@ uint32_t smb_ioport_readb(void *opaque, uint32_t addr)
>>      return val;
>>  }
>>  
>> +static const MemoryRegionOps pm_smbus_ops = {
>> +    .read = smb_ioport_readb,
>> +    .write = smb_ioport_writeb,
>> +    .valid.min_access_size = 1,
>> +    .valid.max_access_size = 1,
>> +    .endianness = DEVICE_LITTLE_ENDIAN,
>> +};
> 
> I notice that in comparison to Julien's patch, you are setting .valid
> here where he used .impl.

Setting .valid matches previous behavior (only byte handlers registered).

I'm not fully sure what the defaults for .valid are in case only .impl
is specified.  I usually either set .valid only or explicitly specify
both if I want the memory api split dword writes into bytes for me.

> Also a generic C question: When using C99-style struct initializers as
> for the MemoryRegionOps, I understand that the fields not explicitly
> assigned are zero-initialized. Does that also apply to .foo.bar = baz
> notation or would it be advisable to use nested .foo = { .bar = baz }?

As far I know the whole (outer) struct is zero-initialized.

cheers,
  Gerd