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Wed, 03 Jun 2020 19:39:54 -0800 Received: from MTKMBS01N1.mediatek.inc (172.21.101.68) by MTKMBS62N2.mediatek.inc (172.29.193.42) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Wed, 3 Jun 2020 20:39:55 -0700 Received: from mtkcas08.mediatek.inc (172.21.101.126) by mtkmbs01n1.mediatek.inc (172.21.101.68) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Thu, 4 Jun 2020 11:39:46 +0800 Received: from [172.21.77.33] (172.21.77.33) by mtkcas08.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.0.1497.2 via Frontend Transport; Thu, 4 Jun 2020 11:39:46 +0800 Message-ID: <1591241986.29475.18.camel@mtkswgap22> Subject: Re: [PATCH] mm/memblock: export max_pfn for kernel modules From: Miles Chen To: Mike Rapoport Date: Thu, 4 Jun 2020 11:39:46 +0800 In-Reply-To: <20200603170624.GA202648@linux.ibm.com> References: <20200603161132.2441-1-miles.chen@mediatek.com> <20200603170624.GA202648@linux.ibm.com> X-Mailer: Evolution 3.2.3-0ubuntu6 MIME-Version: 1.0 X-MTK: N X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200603_203959_687652_7FC6A324 X-CRM114-Status: GOOD ( 16.36 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: wsd_upstream@mediatek.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-mediatek@lists.infradead.org, Matthias Brugger , Andrew Morton , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, 2020-06-03 at 20:06 +0300, Mike Rapoport wrote: > 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/medhttps://lkml.org/lkml/2020/5/30/123ia/ > 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)); > Thanks for the suggestion. totalram_pages() works and I can follow this example. Miles > > > 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 > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel