From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 12A7AC433B4 for ; Thu, 1 Apr 2021 21:20:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C57E5610F8 for ; Thu, 1 Apr 2021 21:20:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234743AbhDAVUS (ORCPT ); Thu, 1 Apr 2021 17:20:18 -0400 Received: from pegase1.c-s.fr ([93.17.236.30]:20963 "EHLO pegase1.c-s.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234114AbhDAVUR (ORCPT ); Thu, 1 Apr 2021 17:20:17 -0400 Received: from localhost (mailhub1-int [192.168.12.234]) by localhost (Postfix) with ESMTP id 4FB4Cb1lVsz9v3Xp; Thu, 1 Apr 2021 15:43:55 +0200 (CEST) X-Virus-Scanned: Debian amavisd-new at c-s.fr Received: from pegase1.c-s.fr ([192.168.12.234]) by localhost (pegase1.c-s.fr [192.168.12.234]) (amavisd-new, port 10024) with ESMTP id yxEuLDOMoY9i; Thu, 1 Apr 2021 15:43:55 +0200 (CEST) Received: from messagerie.si.c-s.fr (messagerie.si.c-s.fr [192.168.25.192]) by pegase1.c-s.fr (Postfix) with ESMTP id 4FB4Cb0Hxbz9v3Xj; Thu, 1 Apr 2021 15:43:55 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 986D08BB1D; Thu, 1 Apr 2021 15:43:54 +0200 (CEST) X-Virus-Scanned: amavisd-new at c-s.fr Received: from messagerie.si.c-s.fr ([127.0.0.1]) by localhost (messagerie.si.c-s.fr [127.0.0.1]) (amavisd-new, port 10023) with ESMTP id Ym_JGFu42o0b; Thu, 1 Apr 2021 15:43:54 +0200 (CEST) Received: from [192.168.4.90] (unknown [192.168.4.90]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 0E8BA8B99D; Thu, 1 Apr 2021 15:43:54 +0200 (CEST) Subject: Re: [PATCH] powerpc/8xx: Load modules closer to kernel text To: Michael Ellerman , Benjamin Herrenschmidt , Paul Mackerras Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, Jordan Niethe References: <87czvf788t.fsf@mpe.ellerman.id.au> <87ft0a1v5i.fsf@mpe.ellerman.id.au> From: Christophe Leroy Message-ID: <7ff6c893-8dcb-3908-3b6c-7172bc224c77@csgroup.eu> Date: Thu, 1 Apr 2021 15:43:52 +0200 User-Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.9.0 MIME-Version: 1.0 In-Reply-To: <87ft0a1v5i.fsf@mpe.ellerman.id.au> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: fr Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Le 01/04/2021 à 06:33, Michael Ellerman a écrit : > Christophe Leroy writes: >> Le 31/03/2021 à 15:39, Michael Ellerman a écrit : >>> Christophe Leroy writes: >>>> On the 8xx, TASK_SIZE is 0x80000000. The space between TASK_SIZE and >>>> PAGE_OFFSET is not used. >>>> >>>> Use it to load modules in order to minimise the distance between >>>> kernel text and modules and avoid trampolines in modules to access >>>> kernel functions or other module functions. >>>> >>>> Define a 16Mbytes area for modules, that's more than enough. >>> >>> 16MB seems kind of small. >>> >>> At least on 64-bit we could potentially have hundreds of MBs of modules. >>> >> >> Well, with a 16 MB kernel and 16 MB modules, my board is full :) > > Heh. ARM set it to 16M or 8M. > >> Even on the more recent board that has 128 MB, I don't expect more than a few MBs of modules in >> addition to the kernel which is approx 8M. >> >> But ok, I'll do something more generic, though it will conflict with Jordan's series. > > Don't feel you have to. You're the expert on 8xx, not me. > Doing it generic allows to also get it on book3s/32 for free. Christophe