On Mon, Jan 07, 2019 at 08:29:38AM -0800, David Miller wrote:

From: Eugene Syromiatnikov <redacted>
Date: Mon, 7 Jan 2019 16:22:29 +0100

quoted

Otherwise it is impossible to use it for something else, as it will break
userspace that puts garbage there.

The same check should be done in other structures, but the fact that
data in reserved fields is ignored is already part of the kernel ABI.

Signed-off-by: Eugene Syromiatnikov <redacted>

I think the opportunity to enforce this has passed and you will break
userspace by doing this.

Does this seriously mean that the 'rsv' field in

	struct ptp_extts_request {
		unsigned int index;  /* Which channel to configure. */
		unsigned int flags;  /* Bit field for PTP_xxx flags. */
		unsigned int rsv[2]; /* Reserved for future use. */
	};

can never be extended with some semantics?

Thanks,
Richard