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DragonFly kernel List (threaded) for 2011-06
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Re: [gsoc] Virtio block device driver


From: Tim Bisson <bissont@xxxxxxx>
Date: Wed, 01 Jun 2011 21:26:24 -0700

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



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