Problems with SG_IO ioctls on sd device (verses sg device)

[Alan Cox]

On Wed, Jan 26, 2005 at 11:40:13AM +1100, Burn Alting wrote:
> allocates paged aligned memory and then forms a 512 block write to
> location 1 on the target. Directly after a reboot of the kernel,
> the ioctl() write to /dev/sda works, but the next time it fails
> with an EINVAL result.

This is an expected and known limitation of the ioctl interface
currently.