Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752405AbbFCC6O (ORCPT ); Tue, 2 Jun 2015 22:58:14 -0400 Received: from mga14.intel.com ([192.55.52.115]:26014 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751599AbbFCC6J (ORCPT ); Tue, 2 Jun 2015 22:58:09 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.13,544,1427785200"; d="scan'208";a="739859349" Date: Tue, 2 Jun 2015 20:09:56 -0700 From: Bin Gao To: "Anderson, Stuart R" Cc: Thomas Gleixner , Ingo Molnar , Ingo Molnar , "H. Peter Anvin" , Greg Kroah-Hartman , One Thousand Gnomes , Peter Hurley , Jiri Slaby , Borislav Petkov , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH v5 2/2] arch/x86: remove pci uart early console from early_prink.c Message-ID: <20150603030956.GB119305@worksta> References: <20150529184123.GB13090@worksta> <20150602115433.GA20697@gmail.com> <20150602192036.GA52512@worksta> <20150602224305.GB64269@worksta> <518B79536261F8469CEA9CC56FA8F74503353E1D@FMSMSX105.amr.corp.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <518B79536261F8469CEA9CC56FA8F74503353E1D@FMSMSX105.amr.corp.intel.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: 1453 Lines: 30 On Wed, Jun 03, 2015 at 12:16:36AM +0000, Anderson, Stuart R wrote: > Bin, et al, > > What we are losing here is the ability to specify a UART by its bus address > instead of just supplying the memory or io address. There are some cases > where this is useful, though I admit it is probably not going to be widely > used. I have seen a platform where the location of the UART moves depending > on the firmware version, but the bus address (B:D.F) did not change. There > are also some platforms where you do not know the address until you boot the > OS and can use the UART to login and find the address of the UART (oops. > Chicken and egg problem). > > Also, I was going to soon send a patch to allow "pciserial32" for the case where the UART registers are 32-bit aligned instead of 8-bit aligned. > > Stuart > Theare are several reasons that we want to move it to serial_core. First, pci is arch independent, so putting these codes in serial_core (which is arch independent) makes more sense. Second, B:D.F may change across SoCs, then to support new SoC we only need change command line but don't need to change the code. Lastly, there could be other non-x86 platforms using it in the future. -Bin -- 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/