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From: Gerd Hoffmann <kraxel@redhat.com>
Date: Mon, 29 Jun 2015 15:35:59 +0200
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Subject: Re: [Qemu-devel] [SeaBIOS] [PATCH 05/18] virtio: add version 1.0
 structs and #defines
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To: Kevin O'Connor <kevin@koconnor.net>
Cc: seabios@seabios.org, qemu-devel@nongnu.org, "Michael S. Tsirkin" <mst@redhat.com>

  Hi,

> > +typedef struct virtio_pci_common_cfg {
> > +    /* About the whole device. */
> > +    u32 device_feature_select;   /* read-write */
> 
> If I understand these structs correctly, they don't reside in memory,
> but instead represent an interface layout and are used with offsetof()
> and sizeof().

Correct.

> If so, I think they should be marked with PACKED.

They are carefully ordered and padded so that adding PACKED should not
change anything.  The linux kernel has them without PACKED too.

> BTW, it would be nice (but certainly not required) to move these types
> of interface definitions to a new virtio header in the std/ directory.

Can do that.

cheers,
  Gerd