On Thu, 25 Oct 2012 15:18:00 +0100, Russell King - ARM Linux wrote: > On Thu, Oct 25, 2012 at 03:56:33PM +0200, Jean Delvare wrote: > > The original idea of using the hole in the i2c_msg structure is from > > David Brownell, who was apparently familiar with such practice, so I > > assumed it was OK. Actually I still assume it is, until someone comes > > with an supported architecture where it is not. > > According to Al Viro, that would be m68k. OK... So to make things clear, let me ask Al directly about it. Al, can you please tell us if: --- a/include/uapi/linux/i2c.h +++ b/include/uapi/linux/i2c.h struct i2c_msg { __u16 addr; /* slave address */ __u16 flags; __u16 len; /* msg length */ + __u16 transferred; /* actual bytes transferred */ __u8 *buf; /* pointer to msg data */ }; would break binary compatibility on m68k or any other architecture you are familiar with? Note that struct i2c_msg isn't declared with attribute packed, so my assumption was that pointer "buf" was align on at least 4 bytes, leaving a hole between len and buf. Am I wrong? Thanks, -- Jean Delvare -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html