diff --git a/projects/rocr-runtime/src/fmm.c b/projects/rocr-runtime/src/fmm.c
index e89290bcd6..fcc234ee9c 100644
--- a/projects/rocr-runtime/src/fmm.c
+++ b/projects/rocr-runtime/src/fmm.c
@@ -40,7 +40,7 @@
 #define INIT_MANAGEBLE_APERTURE(base_value, limit_value) {	\
 	.base = (void *) base_value,				\
 	.limit = (void *) limit_value,				\
-	.align = PAGE_SIZE,					\
+	.align = 0,						\
 	.guard_pages = 1,					\
 	.vm_ranges = NULL,					\
 	.vm_objects = NULL,					\
@@ -1392,11 +1392,14 @@ static int fmm_set_memory_policy(uint32_t gpu_id, int default_policy, int alt_po
 
 static uint32_t get_vm_alignment(uint32_t device_id)
 {
+	int page_size = 0;
+
 	if (device_id >= 0x6920 && device_id <= 0x6939) /* Tonga */
-		return TONGA_PAGE_SIZE;
-	if (device_id >= 0x9870 && device_id <= 0x9877) /* Carrizo */
-		return TONGA_PAGE_SIZE;
-	return PAGE_SIZE;
+		page_size = TONGA_PAGE_SIZE;
+	else if (device_id >= 0x9870 && device_id <= 0x9877) /* Carrizo */
+		page_size = TONGA_PAGE_SIZE;
+
+	return MAX(PAGE_SIZE, page_size);
 }
 
 HSAKMT_STATUS fmm_init_process_apertures(unsigned int NumNodes)
diff --git a/projects/rocr-runtime/src/globals.c b/projects/rocr-runtime/src/globals.c
index d055cecbde..15d6f11456 100644
--- a/projects/rocr-runtime/src/globals.c
+++ b/projects/rocr-runtime/src/globals.c
@@ -32,3 +32,5 @@ unsigned long kfd_open_count;
 unsigned long system_properties_count;
 pthread_mutex_t hsakmt_mutex = PTHREAD_MUTEX_INITIALIZER;
 bool is_dgpu = false;
+int PAGE_SIZE;
+int PAGE_SHIFT;
diff --git a/projects/rocr-runtime/src/libhsakmt.h b/projects/rocr-runtime/src/libhsakmt.h
index 437cf14582..be57fc59f1 100644
--- a/projects/rocr-runtime/src/libhsakmt.h
+++ b/projects/rocr-runtime/src/libhsakmt.h
@@ -49,8 +49,9 @@ extern bool is_dgpu;
 #define CHECK_KFD_OPEN() \
 	do { if (kfd_open_count == 0) return HSAKMT_STATUS_KERNEL_IO_CHANNEL_NOT_OPENED; } while (0)
 
-#define PAGE_SIZE 4096
-#define PAGE_SHIFT 12
+extern int PAGE_SIZE;
+extern int PAGE_SHIFT;
+
 /* VI HW bug requires this virtual address alignment */
 #define TONGA_PAGE_SIZE 0x8000
 
@@ -111,6 +112,14 @@ extern int kmtIoctl(int fd, unsigned long request, void *arg);
 #define VOID_PTR_SUB(ptr,n) (void*)((uint8_t*)(ptr) - n)/*ptr - offset*/
 #define VOID_PTRS_SUB(ptr1,ptr2) (uint64_t)((uint8_t*)(ptr1) - (uint8_t*)(ptr2)) /*ptr1 - ptr2*/
 
+#define MIN(a, b) ({				\
+	typeof(a) tmp1 = (a), tmp2 = (b);	\
+	tmp1 < tmp2 ? tmp1 : tmp2; })
+
+#define MAX(a, b) ({				\
+	typeof(a) tmp1 = (a), tmp2 = (b);	\
+	tmp1 > tmp2 ? tmp1 : tmp2; })
+
 void clear_events_page(void);
 void fmm_clear_all_mem(void);
 void clear_process_doorbells(void);
diff --git a/projects/rocr-runtime/src/openclose.c b/projects/rocr-runtime/src/openclose.c
index 3e0f5a8267..087fbdc36d 100644
--- a/projects/rocr-runtime/src/openclose.c
+++ b/projects/rocr-runtime/src/openclose.c
@@ -31,6 +31,7 @@
 #include <fcntl.h>
 #include <unistd.h>
 #include <stdio.h>
+#include <strings.h>
 #include "fmm.h"
 
 static const char kfd_device_name[] = "/dev/kfd";
@@ -69,6 +70,12 @@ static void clear_after_fork(void)
 	kfd_open_count = 0;
 }
 
+static inline void init_page_size(void)
+{
+	PAGE_SIZE = sysconf(_SC_PAGESIZE);
+	PAGE_SHIFT = ffs(PAGE_SIZE) - 1;
+}
+
 HSAKMT_STATUS
 HSAKMTAPI
 hsaKmtOpenKFD(void)
@@ -99,6 +106,8 @@ hsaKmtOpenKFD(void)
 			goto open_failed;
 		}
 
+		init_page_size();
+
 		result = topology_sysfs_get_system_props(&sys_props);
 		if (result != HSAKMT_STATUS_SUCCESS)
 			goto topology_sysfs_failed;
diff --git a/projects/rocr-runtime/src/topology.c b/projects/rocr-runtime/src/topology.c
index 99460f49ef..bcd25f91d6 100644
--- a/projects/rocr-runtime/src/topology.c
+++ b/projects/rocr-runtime/src/topology.c
@@ -38,8 +38,7 @@
 
 #include "libhsakmt.h"
 #include "fmm.h"
-#define PAGE_SIZE 4096
-#define MIN(X,Y) ((X) < (Y) ? (X) : (Y))
+
 /* Number of memory banks added by thunk on top of topology */
 #define NUM_OF_IGPU_HEAPS 3
 #define NUM_OF_DGPU_HEAPS 3