I added a printk in virtio_ring.c near the BUG_ON check and the vring.num
value is zero. I can't understand why.
-Earlence
On Sun, Jun 9, 2013 at 5:16 PM, Earlence Fernandes
<earlencefe...@gmail.com>wrote:
> This is the code for my probe function:
>
> static int virtsyscalldev_probe(struct virtio_device *vdev)
> {
> struct virtio_syscalldev *vsdd;
> struct virtqueue *vqs[1];
> struct scatterlist sg[1];
> int err, nvqs;
> vq_callback_t *callbacks[] = { fromhost_dosyscall };
> const char *names[] = { "dosyscall_q" };
> vdev->priv = vsdd = kmalloc(sizeof(*vsdd), GFP_KERNEL);
> if(!vsdd)
> {
> err = -ENOMEM;
> goto out;
> }
> vsdd->vdev = vdev; //cache the virtio_device
> err = vdev->config->find_vqs(vdev, nvqs, vqs, callbacks, names);
> if(err)
> goto out_free_vsdd;
> vsdd->input_q = vqs[0];
> /*
> prime the input_q with a buffer so the hypervisor (host) can signal
> us by placing data into it and inducing an interrupt
> */
> sg_init_one(sg, vsdd->inbuff, sizeof(vsdd->inbuff));
> printk(KERN_INFO "buffer ready to prime3\n");
> if(virtqueue_add_buf(vsdd->input_q, sg, 0, 1, vsdd) < 0)
> {
> printk(KERN_ERR "OOOOOOOOOOOOPS\n");
> BUG();
> }
> //buffer has been loaded in the vq, so now kick it
> //and hence notify the hypervisor (host)
> virtqueue_kick(vsdd->input_q);
> return 0;
> out_free_vsdd:
> kfree(vsdd);
> out:
> return err;
> }
>
> The syscalldev struct has a char buffer.
> In the launcher, I created a single virtqueue like so:
>
> add_virtqueue(dev, VIRTQUEUE_NUM, syscall_toguest);
>
> I still get the BUG message. Any idea why?
>
> -Earlence
>
>
> On Sat, Jun 8, 2013 at 11:38 PM, Earlence Fernandes <
> earlencefe...@gmail.com> wrote:
>
>> I am trying to achieve only host->guest communication and so I've created
>> a virtio driver for the guest kernel which calls virtio_add_buf_gfp with
>> one inbuf and 0 outbufs.
>>
>> Whenever I boot the system, lguest crashes complaining of a kernel BUG.
>> At the line specified in virtio_ring.c, I see the following:
>>
>> BUG_ON(out + in > vq->vring.num);
>>
>> From this, it seems to me that I need more vrings than buffers.
>>
>> So, how do I have a channel from the host launcher to the guest kernel
>> with only one queue which is used to send data exclusively into the guest?
>>
>> I've been following virtio_balloon as an example.
>>
>> -Earlence
>>
>
>
_______________________________________________
Lguest mailing list
Lguest@lists.ozlabs.org
https://lists.ozlabs.org/listinfo/lguest
