Recent core ioremap changes require HAVE_ARCH_HUGE_VMAP subscribing archs
provide arch_ioremap_p4d_supported() failing which will result in a build
failure like the following.

ld: lib/ioremap.o: in function `.ioremap_huge_init':
ioremap.c:(.init.text+0x3c): undefined reference to
`.arch_ioremap_p4d_supported'

This defines a stub implementation for arch_ioremap_p4d_supported() keeping
it disabled for now to fix the build problem.

Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <redacted>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: "Aneesh Kumar K.V" <redacted>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Stephen Rothwell <redacted>
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-next@vger.kernel.org

Signed-off-by: Anshuman Khandual <redacted>
---
This has been just build tested and fixes the problem reported earlier.

 arch/powerpc/mm/book3s64/radix_pgtable.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/powerpc/mm/book3s64/radix_pgtable.c b/arch/powerpc/mm/book3s64/radix_pgtable.c
index 8904aa1..c81da88 100644
--- a/arch/powerpc/mm/book3s64/radix_pgtable.c
+++ b/arch/powerpc/mm/book3s64/radix_pgtable.c

@@ -1124,6 +1124,11 @@ void radix__ptep_modify_prot_commit(struct vm_area_struct *vma,
 	set_pte_at(mm, addr, ptep, pte);
 }
 
+int __init arch_ioremap_p4d_supported(void)
+{
+	return 0;
+}
+
 int __init arch_ioremap_pud_supported(void)
 {
 	/* HPT does not cope with large pages in the vmalloc area */

-- 
2.7.4