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Wed, 03 Jun 2020 17:06:31 +0000 Received: from d06av23.portsmouth.uk.ibm.com (d06av23.portsmouth.uk.ibm.com [9.149.105.59]) by b06cxnps4075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 053H6SvZ852442 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 3 Jun 2020 17:06:29 GMT Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id E31EDA4057; Wed, 3 Jun 2020 17:06:28 +0000 (GMT) Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 4197BA404D; Wed, 3 Jun 2020 17:06:27 +0000 (GMT) Received: from linux.ibm.com (unknown [9.145.63.43]) by d06av23.portsmouth.uk.ibm.com (Postfix) with ESMTPS; Wed, 3 Jun 2020 17:06:27 +0000 (GMT) Date: Wed, 3 Jun 2020 20:06:24 +0300 From: Mike Rapoport To: Miles Chen Cc: Andrew Morton , Matthias Brugger , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org, wsd_upstream@mediatek.com Subject: Re: [PATCH] mm/memblock: export max_pfn for kernel modules Message-ID: <20200603170624.GA202648@linux.ibm.com> References: <20200603161132.2441-1-miles.chen@mediatek.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200603161132.2441-1-miles.chen@mediatek.com> X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.216,18.0.687 definitions=2020-06-03_13:2020-06-02,2020-06-03 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1011 suspectscore=1 adultscore=0 mlxscore=0 spamscore=0 mlxlogscore=999 impostorscore=0 phishscore=0 lowpriorityscore=0 priorityscore=1501 bulkscore=0 malwarescore=0 cotscore=-2147483648 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2004280000 definitions=main-2006030133 X-Rspamd-Queue-Id: 99611180424AF X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam05 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Jun 04, 2020 at 12:11:32AM +0800, Miles Chen wrote: > max_pfn is uesd to get the highest pfn in the system. Drivers like > drivers/iommu/mtk_iommu.c checks max_pfn to see if it should enable > its "4GB mode". > > This patch exports the max_pfn symbol, so we can build the driver as > a kernel module. You can use totalram_pages(), like e.g. drivers/media/platform/mtk-vpu/mtk_vpu.c: $ git grep -np totalram_pages drivers/media/ drivers/media/platform/mtk-vpu/mtk_vpu.c=779=static int mtk_vpu_probe(struct platform_device *pdev) drivers/media/platform/mtk-vpu/mtk_vpu.c:861: vpu->enable_4GB = !!(totalram_pages() > (SZ_2G >> PAGE_SHIFT)); > Signed-off-by: Miles Chen > --- > mm/memblock.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/mm/memblock.c b/mm/memblock.c > index c79ba6f9920c..3b2b21ecebb6 100644 > --- a/mm/memblock.c > +++ b/mm/memblock.c > @@ -99,6 +99,7 @@ EXPORT_SYMBOL(contig_page_data); > unsigned long max_low_pfn; > unsigned long min_low_pfn; > unsigned long max_pfn; > +EXPORT_SYMBOL(max_pfn); > unsigned long long max_possible_pfn; > > static struct memblock_region memblock_memory_init_regions[INIT_MEMBLOCK_REGIONS] __initdata_memblock; > -- > 2.18.0 -- Sincerely yours, Mike.