Re: [Qemu-devel] [TestDays] s390x emulation error

[Alexander Graf]

Am 10.11.2011 um 00:17 schrieb Andreas Färber <address@hidden>:

> Am 09.11.2011 23:53, schrieb Andreas Färber:
>> I get the following error:
>> 
>> $ s390x-softmmu/qemu-system-s390x
>> qemu-system-s390x: Guest moved used index from 0 to 47802
> 
> This is coming from hw/virtio.c:
> 
> static int virtqueue_num_heads(VirtQueue *vq, unsigned int idx)
> {
>    uint16_t num_heads = vring_avail_idx(vq) - idx;
> 
>    /* Check it isn't doing very strange things with descriptor numbers. */
>    if (num_heads > vq->vring.num) {
>        error_report("Guest moved used index from %u to %u",
>                     idx, vring_avail_idx(vq));
>        exit(1);
>    }
> 
>    return num_heads;
> }
> 
> Any idea? Couldn't find a related s390-specific patch on the list.

There is a good chance my simple in-zipl virtio implementation does something 
wrong :(. IIRC I always keep the outstanding requests on 1 (something 
outstanding) or 0 (all is done) so I can keep the logic a lot easier.

Alex

> 
> Andreas
> 
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