Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757288AbaKTKDR (ORCPT ); Thu, 20 Nov 2014 05:03:17 -0500 Received: from bhuna.collabora.co.uk ([93.93.135.160]:60990 "EHLO bhuna.collabora.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755849AbaKTKDO (ORCPT ); Thu, 20 Nov 2014 05:03:14 -0500 Message-ID: <546DBC5B.803@collabora.co.uk> Date: Thu, 20 Nov 2014 11:03:07 +0100 From: Javier Martinez Canillas User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Icedove/31.0 MIME-Version: 1.0 To: Olof Johansson CC: One Thousand Gnomes , Lee Jones , Doug Anderson , Bill Richardson , Simon Glass , Gwendal Grignou , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH 1/3] mfd: cros_ec: Add Chrome OS EC userspace device interface References: <1416238213-15263-1-git-send-email-javier.martinez@collabora.co.uk> <1416238213-15263-2-git-send-email-javier.martinez@collabora.co.uk> <20141118170001.6256c6df@lxorguk.ukuu.org.uk> <546CE366.1030405@collabora.co.uk> In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello Olof, On 11/19/2014 09:45 PM, Olof Johansson wrote: >> Is true that this is a new API for mainline but there is a lot of ChromeOS >> installations that depends on this API which means that just replacing the >> kernel with a mainline one there, will break existing user-space programs. > > I think we can deal with that, at least if we pick new ioctl numbers > so we can tell from the userspace tool which interface is in use > during transition. > >> But I understand that since those binaries were using a non-ustream kernel >> it is expected that the kernel API could be changed. >> >> I think it would be great to keep existing binaries working but if changing >> the API is required, then I can certainly do that when doing a re-spin. > > I think there's some value in that, but i'm also somewhat embarrassed > to have missed this aspect when doing internal review, and do agree > with Alan. :) And we have only a few tools that use this interface so > we should be able to cope with it. > > Thanks a lot for your feedback. I'll follow Alan suggestion then and make the structs to be 64-bit safe and properly padded. Also, I'll follow your suggestion and use a different magic number for the IOCTLs so user-space programs can be backward compatible if needed. > -Olof > Best regards, Javier -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/