x86: add hugepagesz option on 64-bit

Add an hugepagesz=...  option similar to IA64, PPC etc.  to x86-64.

This finally allows to select GB pages for hugetlbfs in x86 now that all
the infrastructure is in place.

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 17 insertions, 0 deletions

diff --git a/arch/x86/mm/hugetlbpage.c b/arch/x86/mm/hugetlbpage.c
index b7a65a07af0..8f307d914c2 100644
--- a/arch/x86/mm/hugetlbpage.c
+++ b/arch/x86/mm/hugetlbpage.c
@@ -425,3 +425,20 @@ hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
 
 #endif /*HAVE_ARCH_HUGETLB_UNMAPPED_AREA*/
 
+#ifdef CONFIG_X86_64
+static __init int setup_hugepagesz(char *opt)
+{
+        unsigned long ps = memparse(opt, &opt);
+        if (ps == PMD_SIZE) {
+                hugetlb_add_hstate(PMD_SHIFT - PAGE_SHIFT);
+        } else if (ps == PUD_SIZE && cpu_has_gbpages) {
+                hugetlb_add_hstate(PUD_SHIFT - PAGE_SHIFT);
+        } else {
+                printk(KERN_ERR "hugepagesz: Unsupported page size %lu M\n",
+                        ps >> 20);
+                return 0;
+        }
+        return 1;
+}
+__setup("hugepagesz=", setup_hugepagesz);
+#endif