Re: [PATCH RFC] virtio-pci: new config layout: using memory BAR

[Paolo Bonzini <pbonzini@redhat.com>]

Il 29/05/2013 15:24, Michael S. Tsirkin ha scritto:
> You expect a compiler to pad this structure:
> 
> struct foo {
> 	uint8_t a;
> 	uint8_t b;
> 	uint16_t c;
> 	uint32_t d;
> };
> 
> I'm guessing any compiler that decides to waste memory in this way
> will quickly get dropped by users and then we won't worry
> about building QEMU with it.

You know the virtio-pci config structures are padded, but not all of
them are.  For example, virtio_balloon_stat is not padded and indeed has
an __attribute__((__packed__)) in the spec.

For this reason I prefer to have the attribute everywhere.  So people
don't have to wonder why it's here and not there.

Paolo