From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752516AbbJFOKl (ORCPT ); Tue, 6 Oct 2015 10:10:41 -0400 Received: from 2.236.17.93.rev.sfr.net ([93.17.236.2]:46500 "EHLO mailhub1.si.c-s.fr" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752285AbbJFOKi (ORCPT ); Tue, 6 Oct 2015 10:10:38 -0400 Subject: Re: [PATCH v2 11/25] powerpc/8xx: map 16M RAM at startup To: Scott Wood References: <20150928235846.GF6161@home.buserror.net> Cc: Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org From: Christophe Leroy Message-ID: <5613D65C.7040301@c-s.fr> Date: Tue, 6 Oct 2015 16:10:36 +0200 User-Agent: Mozilla/5.0 (Windows NT 5.1; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 MIME-Version: 1.0 In-Reply-To: <20150928235846.GF6161@home.buserror.net> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Le 29/09/2015 01:58, Scott Wood a écrit : > On Tue, Sep 22, 2015 at 06:50:50PM +0200, Christophe Leroy wrote: >> On recent kernels, with some debug options like for instance >> CONFIG_LOCKDEP, the BSS requires more than 8M memory, allthough >> the kernel code fits in the first 8M. >> Today, it is necessary to activate CONFIG_PIN_TLB to get more than 8M >> at startup, allthough pinning TLB is not necessary for that. >> >> This patch adds a second 8M page to the initial mapping in order to >> have 16M mapped regardless of CONFIG_PIN_TLB, like several other >> 32 bits PPC (40x, 601, ...) >> >> Signed-off-by: Christophe Leroy >> --- > Is the assumption that nobody is still running 8xx systems with only 8 > MiB RAM on current kernels? > > No, setup_initial_memory_limit() limits the memory to the minimum between 16M and the real memory size, so if a platform has only 8M, it will still be limited to 8M even with 16M mapped. Christophe