Rusty,

I currently try to make my guest boot from an virtio root device
without having an external kernel. Some of the tools that I tried 
expect HDIO_GETGEO to work. The most interesting value is likely
the geo.start value to get the offset of a partition. This value
is filled by block/ioctl.c if fops->getgeo is set. This patch also
fills in some standard values for heads, sectors and cylinders.

Makes sense?

Signed-off-by: Christian Borntraeger <[EMAIL PROTECTED]>
---
 drivers/block/virtio_blk.c |   15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

Index: kvm/drivers/block/virtio_blk.c
===================================================================
--- kvm.orig/drivers/block/virtio_blk.c
+++ kvm/drivers/block/virtio_blk.c
@@ -154,9 +154,20 @@ static int virtblk_ioctl(struct inode *i
                              (void __user *)data);
 }
 
+/* We provide getgeo only to please some old bootloader/partitioning tools */
+static int virtblk_getgeo(struct block_device *bd, struct hd_geometry *geo)
+{
+       /* some standard values, similar to sd */
+       geo->heads = 1 << 6;
+       geo->sectors = 1 << 5;
+       geo->cylinders = get_capacity(bd->bd_disk) >> 11;
+       return 0;
+}
+
 static struct block_device_operations virtblk_fops = {
-       .ioctl = virtblk_ioctl,
-       .owner = THIS_MODULE,
+       .ioctl  = virtblk_ioctl,
+       .owner  = THIS_MODULE,
+       .getgeo = virtblk_getgeo,
 };
 
 static int virtblk_probe(struct virtio_device *vdev)

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