commit ac5a7889d31bb37aa0687110ecea08837f8a66a8
Author: Dave Anderson <anderson@redhat.com>
Date:   Fri Feb 8 10:48:30 2019 -0500

    Support for configurable CONFIG_ARM64_PA_BITS values introduced
    in kernel commit 982aa7c5f0861bf56b2412ca341a13f44c238ba4, titled
    "arm64: add kconfig symbol to configure physical address size".
    Without the patch, it is impossible to determine the value of
    CONFIG_ARM64_PA_BITS, and will require a new MAX_PHYSMEM_BITS
    vmcoreinfo entry to be exported.  This patch reads that entry
    during intitialization.
    (anderson@redhat.com)

diff --git a/arm64.c b/arm64.c
index 2308612..b4d9b13 100644
--- a/arm64.c
+++ b/arm64.c
@@ -362,7 +362,10 @@ arm64_init(int when)
 		arm64_calc_virtual_memory_ranges();
 		machdep->section_size_bits = _SECTION_SIZE_BITS;
 		if (!machdep->max_physmem_bits) {
-			if (machdep->machspec->VA_BITS == 52)  /* guess */
+			if ((string = pc->read_vmcoreinfo("NUMBER(MAX_PHYSMEM_BITS)"))) {
+				machdep->max_physmem_bits = atol(string);
+				free(string);
+			} else if (machdep->machspec->VA_BITS == 52)  /* guess */
 				machdep->max_physmem_bits = _MAX_PHYSMEM_BITS_52;
 			else if (THIS_KERNEL_VERSION >= LINUX(3,17,0)) 
 				machdep->max_physmem_bits = _MAX_PHYSMEM_BITS_3_17;