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=-1.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 EFC19C433DF for ; Thu, 2 Jul 2020 11:48:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BB60D20780 for ; Thu, 2 Jul 2020 11:48:15 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="NNaUC1qy" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728768AbgGBLsO (ORCPT ); Thu, 2 Jul 2020 07:48:14 -0400 Received: from us-smtp-2.mimecast.com ([205.139.110.61]:38714 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726443AbgGBLsO (ORCPT ); Thu, 2 Jul 2020 07:48:14 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1593690492; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=XjmPmaD/IooVKYdxRZ/9YWrdivHE5lwEHMPYLDdNJ+Y=; b=NNaUC1qymoNtsNN2JBZ2AzDpn5UK84iQrJQMUKOGt2GBdQO4KWroO6RjTAvstSMrgwo3hp gmbt1flSDitDWPq/1ee/v6ts4DZFSfGdHIl4LwQJr9MSsVA46vX0es7WtHQwT85JN7Mfsw CpYCY3AHz0UqbSY9DVAzwq02AMpziI0= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-220-H_w9jTJWOV6KaVp1n8h7fg-1; Thu, 02 Jul 2020 07:48:08 -0400 X-MC-Unique: H_w9jTJWOV6KaVp1n8h7fg-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id EC89E107ACF2; Thu, 2 Jul 2020 11:48:06 +0000 (UTC) Received: from dhcp-128-65.nay.redhat.com (ovpn-13-96.pek2.redhat.com [10.72.13.96]) by smtp.corp.redhat.com (Postfix) with ESMTPS id E5D0419D7F; Thu, 2 Jul 2020 11:48:01 +0000 (UTC) Date: Thu, 2 Jul 2020 19:47:58 +0800 From: Dave Young To: Hari Bathini Cc: Thiago Jung Bauermann , Pingfan Liu , Petr Tesarik , Kexec-ml , Mahesh J Salgaonkar , Mimi Zohar , lkml , linuxppc-dev , Sourabh Jain , Andrew Morton , Vivek Goyal , Eric Biederman Subject: Re: [PATCH 01/11] kexec_file: allow archs to handle special regions while locating memory hole Message-ID: <20200702114758.GA21026@dhcp-128-65.nay.redhat.com> References: <159319825403.16351.7253978047621755765.stgit@hbathini.in.ibm.com> <159319828304.16351.6990340111766605842.stgit@hbathini.in.ibm.com> <20200629133933.0787f562@ezekiel.suse.cz> <7981ae61-26c6-000c-9ee4-382dab3eecab@linux.ibm.com> <20200701074659.GA3878@dhcp-128-65.nay.redhat.com> <0e145e84-a6cf-4da3-1a1a-331a7e1ac1fa@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <0e145e84-a6cf-4da3-1a1a-331a7e1ac1fa@linux.ibm.com> X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/02/20 at 12:01am, Hari Bathini wrote: > > > On 01/07/20 1:16 pm, Dave Young wrote: > > On 06/29/20 at 05:26pm, Hari Bathini wrote: > >> Hi Petr, > >> > >> On 29/06/20 5:09 pm, Petr Tesarik wrote: > >>> Hi Hari, > >>> > >>> is there any good reason to add two more functions with a very similar > >>> name to an existing function? AFAICS all you need is a way to call a > >>> PPC64-specific function from within kexec_add_buffer (PATCH 4/11), so > >>> you could add something like this: > >>> > >>> int __weak arch_kexec_locate_mem_hole(struct kexec_buf *kbuf) > >>> { > >>> return 0; > >>> } > >>> > >>> Call this function from kexec_add_buffer where appropriate and then > >>> override it for PPC64 (it roughly corresponds to your > >>> kexec_locate_mem_hole_ppc64() from PATCH 4/11). > >>> > >>> FWIW it would make it easier for me to follow the resulting code. > >> > >> Right, Petr. > >> > >> I was trying out a few things before I ended up with what I sent here. > >> Bu yeah.. I did realize arch_kexec_locate_mem_hole() would have been better > >> after sending out v1. Will take care of that in v2. > > > > Another way is use arch private function to locate mem hole, then set > > kbuf->mem, and then call kexec_add_buf, it will skip the common locate > > hole function. > > Dave, I did think about it. But there are a couple of places this can get > tricky. One is ima_add_kexec_buffer() and the other is kexec_elf_load(). > These call sites could be updated to set kbuf->mem before kexec_add_buffer(). > But the current approach seemed like the better option for it creates a > single point of control in setting up segment buffers and also, makes adding > any new segments simpler, arch-specific segments or otherwise. > Ok, thanks for the explanation.