Re: [PATCH 3/6] firewire: char device interface

Kristian Høgsberg
2007-05-08T00:10:43Z

Christoph Hellwig wrote:
> On Wed, May 02, 2007 at 02:17:26PM +0200, Stefan Richter wrote:
>> +#include <asm/ioctl.h>
>> +#include <asm/types.h>
>
> Always use the <linux/ versions.

Fixed.

>> +struct fw_cdev_get_info {
>> + /* The version field is just a running serial number. We
>> + * never break backwards compatibility. Userspace passes in
>> + * the version it expects and the kernel passes back the
>> + * highest version it can provide. Even if the structs in
>> + * this interface are extended in a later version, the kernel
>> + * will not copy back more data than what was present in the
>> + * interface version userspace expects. */
>> + __u32 version;
>
> Please don't even try to build interfaces this complicated. If your
> current interface needs changes at some point just introduce new ioctls.

Sure, I don't expect a lot of changes anyway, and the few features I know that
will show up down the road are strictly additions anyway. I think it makes
sense to keep the version number there, though, as a way to advertise which
ioctls are present.

Kristian