Re: [Qemu-devel] [PATCH RFC 8/8] virtio: add endian-ambivalent support to VirtIODevice

["Andreas Färber" <afaerber@suse.de>]

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 = 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 != VIRTIO_DEVICE_ENDIAN_UNKNOWN);
>> +    if (target_words_bigendian()) {
>> +        return vdev->device_endian == VIRTIO_DEVICE_ENDIAN_LITTLE;
>> +    } else {
>> +        return vdev->device_endian == VIRTIO_DEVICE_ENDIAN_BIG;
>> +    }
>> +}
>> +
>>  static const VirtIOSubsection virtio_subsection[] = {
>> +    { .name = "virtio/device_endian",
> 
> Can anyone comment the subsection name ? Is there a chance the
> VMState port would come up with the same ?
> 
>> +      .version_id = 1,
>> +      .save = virtio_save_device_endian,
>> +      .load = virtio_load_device_endian,
>> +      .needed = virtio_device_endian_needed,
>> +    },
>>      { .name = 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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