Re: [gsoc] Virtio block device driver

[Tim Bisson <bissont@xxxxxxx>]

On 5/31/11 1:05 PM, Stéphanie Ouillon wrote:
> Hello,
>
> I modified some parts of the code of the virtio block device driver 
> that has been already ported from NetBSD.
> The code is available here : github.com/arroway/virtio_DragonFlyBSD
>
> The initially ported block device driver is available in the block/ 
> direectory : it was working on its own.
> What I did is that I modified it so that it could work with a more 
> general interface, virtio.c
Can you clarify what you mean by make it "work with a more general 
interface, virtio.c"? The block driver as it was, would use virtio.c. 
For example, virtio_negotiate_features() is in virtio.c and is called 
from virtio-blk.c

I'm referring to the last code written for the virtio-block:
http://gitorious.org/virtio-drivers/virtio-drivers/trees/master

> First the virtio module is called, and it detects or not a virtio 
> device. Then, according to the type of the virtio device ( here, a 
> block device ), it calls the virtio_blk module.
>
> I've got some problems to attach my virtio device with virtio_blk.
>
> Here is what I did, as I told my mentor Pratyush  Kshirsagar :
>
> Some functions were defined twice : in virtio_blk.c and in virtio.c. 
> In virtio.c, their prototypes accepted a virtio_softc * structure, but 
> in virtio_blk.c, they wanted a virtio_blk_softc * structure.
> Now, I only use the functions in virtio.c ( I deleted the 
> corresponding functions in virtio_blk.c to keep ony the functions that 
> were specific to the block device ).
>
>  So I changed the definition of virtio_blk_softc * structure in 
> virtio_blk.c. Now it looks like this :
> (like in the netbsd code)
>
> *struct virtio_blk_softc {*
>
>     device_t sc_dev;
>
> *struct virtio_softc *sc_virtio;*
>     struct virtqueue sc_vq[1];
>
>     struct virtio_blk_req    *sc_reqs;
>     int sc_readonly;
>     uint32_t    sc_features;
>     int     maxxfersize;
>
> /    //added : what for ?/
>     bus_dma_segment_t    sc_reqs_segs[1];
> /    //I don't use it at the moment ( virtio_blk_attach() )/
> /    kmutex_t    sc_lock;/
>
> /// Block stuff : for testing/ /with /devstat
>     cdev_t cdev;
>     struct devstat stats;
>     struct disk disk;
>
> *};*

I think you might be using an older version of the virtio block code? In 
the gitorious tree I pointed to earlier, there is a pointer to 
virtio_softc in virtio_blk_softc.

Thanks,
Tim