Makefile

CC=/usr/bin/cc

CFLAGS= -I/opt/X11/include -L/opt/X11/lib -std=iso9899:1999 -m64 -O0 -g -fno-builtin \
        -pedantic -pedantic-errors \
        -march=k8 -mtune=k8 -mieee-fp -mhard-float \
        -fno-fast-math -malign-double \
        -mstackrealign -mno-mmx \

CPPFLAGS=-D_TS_ERRNO -D_POSIX_PTHREAD_SEMANTICS -D_LARGEFILE64_SOURCE \
        -D_X_OPEN_SOURCE=600

LIBS = -lX11 -lm -lpthread

SRCS = ./mandel_col.c ./not_double_r_col.c \
        ./linear_inter.c \
        ./mbrot.c \
        ../xwin/x_error_handler.c \
        ../xwin/create_gc.c \
        ../xwin/create_borderless_topwin.c \
        ../time_and_date/timediff.c \
        ../sysinfo/sysmem.c ../sysinfo/sysinfo.c


OBJS = ./mandel_col.o ./not_double_r_col.o \
        ./linear_inter.o \
        ./mbrot.o \
        ../xwin/x_error_handler.o \
        ../xwin/create_gc.o \
        ../xwin/create_borderless_topwin.o \
        ../time_and_date/timediff.o \
        ../sysinfo/sysmem.o ../sysinfo/sysinfo.o

%.o: %.c
        $(CC) -c -o $@ $< $(CFLAGS) $(CPPFLAGS) -D USE_SYSCTL_HW_MEMSIZE

xmand: xmand.o $(OBJS)
        $(CC) -o $@ $^ $(CFLAGS) $(CPPFLAGS) $(LIBS)

clean:
        rm -f $(OBJS) xmand.o xmand

sysmem.c.diff

diff --git a/sysinfo/sysmem.c b/sysinfo/sysmem.c
index 8ab0439..652e14b 100644
--- a/sysinfo/sysmem.c
+++ b/sysinfo/sysmem.c
@@ -10,7 +10,9 @@
  *    Macro and in addition to enable the XSI extension.
  *
  *********************************************************************/
+#ifndef USE_SYSCTL_HW_MEMSIZE
 #define _XOPEN_SOURCE 600
+#endif
 
 #include <stdio.h>
 #include <stdint.h>
@@ -20,13 +22,25 @@
 #include <stdint.h>
 #include <sys/resource.h>
 
+#if USE_SYSCTL_HW_MEMSIZE
+#include <sys/types.h>
+#include <sys/sysctl.h>
+#endif
+
 uint64_t system_memory()
 {
     /* should return the amount of memory available in bytes */
     long en;
     uint64_t pages, page_size;
 
-    en = sysconf(_SC_PHYS_PAGES);
+    #if USE_SYSCTL_HW_MEMSIZE
+        uint64_t mem;
+        size_t len = sizeof(mem);
+        sysctlbyname("hw.memsize", &mem, &len, NULL, 0);
+        en = mem/sysconf(_SC_PAGE_SIZE);
+    #else
+        en = sysconf(_SC_PHYS_PAGES);
+    #endif
     if ( en < 0 ){
         perror("sysconf(_SC_PHYS_PAGES) : ");
         exit(EXIT_FAILURE);