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Date: Mon, 19 May 2014 19:06:39 +0200
From: =?ISO-8859-1?Q?Andreas_F=E4rber?= <afaerber@suse.de>
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Subject: Re: [Qemu-devel] [PATCH RFC 8/8] virtio: add endian-ambivalent
 support to VirtIODevice
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To: Greg Kurz <gkurz@linux.vnet.ibm.com>
Cc: Kevin Wolf <kwolf@redhat.com>, Fam Zheng <famz@redhat.com>, Anthony Liguori <aliguori@amazon.com>, "Michael S. Tsirkin" <mst@redhat.com>, Juan Quintela <quintela@redhat.com>, Alexander Graf <agraf@suse.de>, qemu-devel@nongnu.org, Stefan Hajnoczi <stefanha@redhat.com>, Amit Shah <amit.shah@redhat.com>, Paolo Bonzini <pbonzini@redhat.com>

Am 19.05.2014 15:06, schrieb Greg Kurz:
> On Mon, 19 May 2014 10:39:09 +0200
> Greg Kurz <gkurz@linux.vnet.ibm.com> wrote:
>> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
>> index 7fbad29..6578854 100644
>> --- a/hw/virtio/virtio.c
>> +++ b/hw/virtio/virtio.c
[...]
>> @@ -839,10 +849,39 @@ typedef struct VirtIOSubsection {
>>      int version_id;
>>      void (*save)(VirtIODevice *vdev, QEMUFile *f);
>>      int (*load)(VirtIODevice *vdev, QEMUFile *f);
>> -    int (*needed)(VirtIODevice *vdev);
>> +    bool (*needed)(VirtIODevice *vdev);
>>  } VirtIOSubsection;
>>
>> +static void virtio_save_device_endian(VirtIODevice *vdev, QEMUFile *f=
)
>> +{
>> +    qemu_put_byte(f, vdev->device_endian);
>> +}
>> +
>> +static int virtio_load_device_endian(VirtIODevice *vdev, QEMUFile *f)
>> +{
>> +    vdev->device_endian =3D qemu_get_byte(f);
>> +    return 0;
>> +}
>> +
>> +static bool virtio_device_endian_needed(VirtIODevice *vdev)
>> +{
>> +    /* No migration is supposed to occur while we are loading state.
>> +     */
>> +    assert(vdev->device_endian !=3D VIRTIO_DEVICE_ENDIAN_UNKNOWN);
>> +    if (target_words_bigendian()) {
>> +        return vdev->device_endian =3D=3D VIRTIO_DEVICE_ENDIAN_LITTLE=
;
>> +    } else {
>> +        return vdev->device_endian =3D=3D VIRTIO_DEVICE_ENDIAN_BIG;
>> +    }
>> +}
>> +
>>  static const VirtIOSubsection virtio_subsection[] =3D {
>> +    { .name =3D "virtio/device_endian",
>=20
> Can anyone comment the subsection name ? Is there a chance the
> VMState port would come up with the same ?
>=20
>> +      .version_id =3D 1,
>> +      .save =3D virtio_save_device_endian,
>> +      .load =3D virtio_load_device_endian,
>> +      .needed =3D virtio_device_endian_needed,
>> +    },
>>      { .name =3D NULL }
>>  };
>>

Different question: With converting VirtIO to VMState in mind, why are
you not using a regular VMStateSubsection and loading/saving that as
part of the old-style load/save functions? Is an API for that missing?

Regards,
Andreas

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