From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mailhub1.si.c-s.fr (2.236.17.93.rev.sfr.net [93.17.236.2]) by lists.ozlabs.org (Postfix) with ESMTP id 547441A0017 for ; Wed, 7 Oct 2015 01:10:39 +1100 (AEDT) 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 MIME-Version: 1.0 In-Reply-To: <20150928235846.GF6161@home.buserror.net> Content-Type: text/plain; charset=windows-1252; format=flowed List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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