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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2EE59C433EF for ; Mon, 11 Apr 2022 08:28:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1343805AbiDKIah (ORCPT ); Mon, 11 Apr 2022 04:30:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51528 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1343797AbiDKIad (ORCPT ); Mon, 11 Apr 2022 04:30:33 -0400 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4ACAD3E5E2 for ; Mon, 11 Apr 2022 01:28:19 -0700 (PDT) Received: from dggpemm500022.china.huawei.com (unknown [172.30.72.54]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4KcMPY62ZDzFpkk; Mon, 11 Apr 2022 16:25:53 +0800 (CST) Received: from dggpemm500001.china.huawei.com (7.185.36.107) by dggpemm500022.china.huawei.com (7.185.36.162) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Mon, 11 Apr 2022 16:28:15 +0800 Received: from [10.174.177.243] (10.174.177.243) by dggpemm500001.china.huawei.com (7.185.36.107) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256) id 15.1.2375.24; Mon, 11 Apr 2022 16:28:15 +0800 Message-ID: <73e5583d-2f32-8837-e32a-93f127f0a40b@huawei.com> Date: Mon, 11 Apr 2022 16:28:14 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.5.1 Subject: Re: [PATCH v2 resend 2/3] arm64: mm: Don't defer reserve_crashkernel() with dma_force_32bit Content-Language: en-US To: Vijay Balakrishna , , , , CC: References: <20220331074055.125824-1-wangkefeng.wang@huawei.com> <20220331074055.125824-3-wangkefeng.wang@huawei.com> From: Kefeng Wang In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.177.243] X-ClientProxiedBy: dggeme701-chm.china.huawei.com (10.1.199.97) To dggpemm500001.china.huawei.com (7.185.36.107) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2022/4/2 6:09, Vijay Balakrishna wrote: > > > On 3/31/2022 12:40 AM, Kefeng Wang wrote: >> ARM64 enable ZONE_DMA by default, and with ZONE_DMA crash kernel >> memory reservation is delayed until DMA zone memory range size >> initilazation performed in zone_sizes_init(), but for most platforms >> use 32bit dma_zone_bits, so add dma_force_32bit kernel parameter >> if ZONE_DMA enabled, and initialize arm64_dma_phys_limit to >> dma32_phys_limit in arm64_memblock_init() if dma_force_32bit >> is setup, this could let the crash kernel reservation earlier, >> and allows linear creation with block mapping. >> >> Signed-off-by: Kefeng Wang > > I don't see any problem with the approach.  Hope you or someone can > test to make sure no surprises on RPi4 with the proposed change.  I do > understand on RPi4 -- > > - both ZONE_DMA and ZONE_DMA32 are enabled > - one wouldn't use dma_force_32bit kernel parameter > - crashkernel_could_early_reserve() would return false to preserve > late reserve of crash kernel memory > I don't have RPi4, I tested following cases on qemu 1) only with ZONE_DMA     1.1) only with ZONE_DMA and with dma_force_32bit 2) only with ZONE_DMA32 3) with ZONE_DMA and ZONE_DMA32    3.1) with ZONE_DMA and ZONE_DMA32 and with dma_force_32bit > nit -- > - consider renaming crashkernel_could_early_reserve() => > crashkernel_early_reserve() > Sure. > Reviewed-by: Vijay Balakrishna > Thanks.