| Message ID | 20200603161132.2441-1-miles.chen@mediatek.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | mm/memblock: export max_pfn for kernel modules | expand |
On 03.06.20 18:11, 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. Please add that change to the respective user patch (and cc MM-people for that patch), so we have the actual user right along the change and can figure out if this is the right thing to do. > > Signed-off-by: Miles Chen <miles.chen@mediatek.com> > --- > 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; >
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@mediatek.com> > --- > 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
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 <miles.chen@mediatek.com> > > --- > > 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 >
On Wed, 2020-06-03 at 18:16 +0200, David Hildenbrand wrote: > On 03.06.20 18:11, 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. > > Please add that change to the respective user patch (and cc MM-people > for that patch), so we have the actual user right along the change and > can figure out if this is the right thing to do. > Thanks for the comment. Mike points out another alternative way to do this by totalram_pages(). I will use that approach so we don't have to export max_pfn here. https://lkml.org/lkml/2020/6/3/771 Miles > > > > Signed-off-by: Miles Chen <miles.chen@mediatek.com> > > --- > > 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; > > > >
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;
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. Signed-off-by: Miles Chen <miles.chen@mediatek.com> --- mm/memblock.c | 1 + 1 file changed, 1 insertion(+)