From mboxrd@z Thu Jan 1 00:00:00 1970 From: Prarit Bhargava Subject: Re: [PATCH] acpi, spcr: Make SPCR available to x86 Date: Mon, 12 Feb 2018 08:47:57 -0500 Message-ID: <1e69fffc-1c3b-8cc0-f1cb-695de5ccdcb5@redhat.com> References: <20180118150951.28964-1-prarit@redhat.com> <20180212133429.GC25314@hirez.programming.kicks-ass.net> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20180212133429.GC25314@hirez.programming.kicks-ass.net> Sender: linux-kernel-owner@vger.kernel.org To: Peter Zijlstra Cc: linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org, linux-doc@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-pm@vger.kernel.org, linux-serial@vger.kernel.org, Bhupesh Sharma , Lv Zheng , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org, Jonathan Corbet , Catalin Marinas , Will Deacon , Timur Tabi , graeme.gregory@linaro.org, mark.salter@redhat.com List-Id: linux-pm@vger.kernel.org On 02/12/2018 08:34 AM, Peter Zijlstra wrote: > On Thu, Jan 18, 2018 at 10:09:51AM -0500, Prarit Bhargava wrote: >> config ACPI_SPCR_TABLE >> + bool "ACPI Serial Port Console Redirection Support" >> + default y if X86 >> + help >> + Enable support for Serial Port Console Redirection (SPCR) Table. >> + This table provides information about the configuration of the >> + earlycon console. > > I just got asked this by oldconfig, which left me rather puzzled, WTF > does this do? Odd -- I thought I had taken care of that :( My apologies Peter. ACPI SPCR is used by a vendor to define the serial console for a system. If SPCR exists a user can add kernel parameter "earlycon" (no extra kernel parameters) and the console will work out-of-the-box. The serial console configuration varies from vendor to vendor. This takes the guess-work out of defining a serial console. P. >