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 <miles.chen@xxxxxxxxxxxx> > --- > 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.
