From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751783AbdDMPvF (ORCPT ); Thu, 13 Apr 2017 11:51:05 -0400 Received: from esa4.dell-outbound.iphmx.com ([68.232.149.214]:40582 "EHLO esa4.dell-outbound.iphmx.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751242AbdDMPvC (ORCPT ); Thu, 13 Apr 2017 11:51:02 -0400 X-Greylist: delayed 570 seconds by postgrey-1.27 at vger.kernel.org; Thu, 13 Apr 2017 11:51:02 EDT From: X-LoopCount0: from 10.175.216.250 X-IronPort-AV: E=Sophos;i="5.37,195,1488866400"; d="scan'208";a="6182840" To: , CC: , , , , , , , , , Subject: RE: RFC: WMI Enhancements Thread-Topic: RFC: WMI Enhancements Thread-Index: AQHSs+HFfWGz3Na/pUazu2XvXvLesqHDPEIAgAANzoCAAFv3AIAAHP4A//+tS8A= Date: Thu, 13 Apr 2017 15:40:08 +0000 Message-ID: <5bdfff4f72a941d086eeebba71557f19@ausx13mpc120.AMER.DELL.COM> References: <20170412230854.GA11963@fury> <20170413073228.GB1462@ozzy.nask.waw.pl> <3370431810bd4bc09fd9eb16eb9abea5@ausx13mpc120.AMER.DELL.COM> <20170413135102.GL3090@pali> In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.208.86.26] Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from base64 to 8bit by mail.home.local id v3DFpFBG018753 > -----Original Message----- > From: Andy Lutomirski [mailto:luto@kernel.org] > Sent: Thursday, April 13, 2017 10:35 AM > To: Pali Rohár > Cc: Limonciello, Mario ; Hans de Goede > ; Michał Kępień ; Darren Hart > ; Rafael J. Wysocki ; Len Brown > ; corentin.chary@gmail.com; Andrew Lutomirski > ; Andy Shevchenko ; > linux-kernel@vger.kernel.org; platform-driver-x86@vger.kernel.org; linux- > pm@vger.kernel.org > Subject: Re: RFC: WMI Enhancements > > On Thu, Apr 13, 2017 at 6:51 AM, Pali Rohár wrote: > > On Thursday 13 April 2017 13:29:41 Mario.Limonciello@dell.com wrote: > >> > Please pardon my ignorance, but what do we actually gain by > >> > exposing WMI to userspace? Enabling applications to fetch SMBIOS > >> > data? We already have an interface for that. Enabling applications to > receive input events? Likewise. > >> > >> Input notifications are just one aspect that received over WMI. I > >> don't see any reason to move the notifications out of the kernel. > >> > >> In terms of userspace applications, once a WMI interface to userspace > >> is available libsmbios would change over to that. Applications using > libsmbios would benefit. > > > > Really libsmbios matters here? Hans (added to thread) wrote that > > libsmbios is a relic, something of ages long gone by and a normal user > > should never use it. > > > > If this is truth and libsmbios should not be used, then we probably do > > not need to care about it in changes for WMI. > > > > Hans, Mario, any comment/clarification about it? > > > >> > You mentioned WMI's efficiency compared to SMI/SMM, but is it a > >> > difference significant enough for anyone to notice? > >> > >> At least for Dell there are optimizations being made when data is > >> requested over the WMI-ACPI wrapper instead of directly via SMI/SMM. > >> > >> For example if the data is a "static" table or the request is to > >> something that is passed thru to the EC it's a big waste of effort to put the > CPU in SMM. > >> > >> The savings there is significant. > > > > Maybe we can use this Dell WMI-ACPI wrapper for kernel drivers instead > > of current SMI/SMM direct access? > > > > This would make sense to me. IIRC the only functional difference is the way > that pointers are handled. It shouldn't be that hard to make it work for both > variants, though. It could look like: > > buf = dell_smbios_alloc(...); > dell_smbios_put_pointer(buf, offset of pointer, offset of pointee); > dell_smbios_call(buf); > > or similar. Yes, I was going to encourage that kernel change after this WMI discussion had some conclusions.