Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932338AbbLBCTt (ORCPT ); Tue, 1 Dec 2015 21:19:49 -0500 Received: from smtp-outbound-1.vmware.com ([208.91.2.12]:49472 "EHLO smtp-outbound-1.vmware.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757399AbbLBCTr (ORCPT ); Tue, 1 Dec 2015 21:19:47 -0500 From: "Sinclair Yeh" Date: Tue, 1 Dec 2015 18:21:06 -0800 To: Greg Kroah-Hartman Cc: Dmitry Torokhov , X86 ML , "pv-drivers@vmware.com" , "linux-graphics-maintainer@vmware.com" , Arnd Bergmann , lkml , virtualization@lists.linux-foundation.org, "linux-input@vger.kernel.org" Subject: Re: [PATCH 3/6] Input: Update vmmouse.c to use the common VMW_PORT macros Message-ID: <20151202022106.GA6471@syeh-linux> References: <1449008047-8252-1-git-send-email-syeh@vmware.com> <1449008332-9394-1-git-send-email-syeh@vmware.com> <1449008332-9394-3-git-send-email-syeh@vmware.com> <20151201222414.GH3740@dtor-ws> <20151201223255.GA10753@syeh-linux> <20151201225420.GA11210@syeh-linux> <20151202000408.GB5363@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20151202000408.GB5363@kroah.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3441 Lines: 79 On Tue, Dec 01, 2015 at 04:04:08PM -0800, Greg Kroah-Hartman wrote: > On Tue, Dec 01, 2015 at 02:54:20PM -0800, Sinclair Yeh wrote: > > Hi, > > > > On Tue, Dec 01, 2015 at 02:45:27PM -0800, Dmitry Torokhov wrote: > > > On Tue, Dec 1, 2015 at 2:32 PM, Sinclair Yeh wrote: > > > > Hi, > > > > > > > > > > > > > >> > */ > > > >> > -#define VMMOUSE_CMD(cmd, in1, out1, out2, out3, out4) \ > > > >> > -({ \ > > > >> > - unsigned long __dummy1, __dummy2; \ > > > >> > - __asm__ __volatile__ ("inl %%dx" : \ > > > >> > - "=a"(out1), \ > > > >> > - "=b"(out2), \ > > > >> > - "=c"(out3), \ > > > >> > - "=d"(out4), \ > > > >> > - "=S"(__dummy1), \ > > > >> > - "=D"(__dummy2) : \ > > > >> > - "a"(VMMOUSE_PROTO_MAGIC), \ > > > >> > - "b"(in1), \ > > > >> > - "c"(VMMOUSE_PROTO_CMD_##cmd), \ > > > >> > - "d"(VMMOUSE_PROTO_PORT) : \ > > > >> > - "memory"); \ > > > >> > +#define VMMOUSE_CMD(cmd, in1, out1, out2, out3, out4) \ > > > >> > +({ \ > > > >> > + unsigned long __dummy1 = 0, __dummy2 = 0; \ > > > >> > > > >> Why do we need to initialize dummies? > > > > > > > > Because for some commands those parameters to VMW_PORT() can be both > > > > input and outout. > > > > > > The vmmouse commands do not use them as input though, so it seems we > > > are simply wasting CPU cycles setting them to 0 just because we are > > > using the new VMW_PORT here. Why do we need to switch? What is the > > > benefit of doing this? > > > > There are two reasons. One is to make the code more readable and > > maintainable. Rather than having mostly similar inline assembly > > code sprinkled across multiple modules, we can just use the macros > > and document that. > > But the macro is only used here, and the variables aren't used at all, > so it makes no sense in this file. Maybe it's because I didn't CC you on the rest of the series. I wasn't sure what the proper distribution list is for each part. This new macro is also used in arch/x86/kernel/cpu/vmware.c and vmw_balloon.c > > > The second reason is this organization makes some on-going future > > development easier. > > We don't plan for "future" development other than a single patch series, > as we have no idea what that development is, nor if it will really > happen. You can always change this file later if you need to, nothing > is keeping that from happening. So the intent of this series is to centralize similar lines of inline assembly code that are currently used by 3 different kernel modules to a central place. The new vmware.h [patch 0/6] becomes the one header to include for common guest-host communication needs. > thanks, > > greg k-h -- 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/