Index: usr.sbin/bsdinstall/partedit/gpart_ops.c
===================================================================
--- usr.sbin/bsdinstall/partedit/gpart_ops.c
+++ usr.sbin/bsdinstall/partedit/gpart_ops.c
@@ -30,6 +30,7 @@
 
 #include <sys/param.h>
 #include <sys/stat.h>
+#include <sys/mman.h>
 #include <errno.h>
 #include <libutil.h>
 #include <inttypes.h>
@@ -376,7 +377,7 @@
 	struct gctl_req *r;
 	const char *errstr, *scheme;
 	uint8_t *boot;
-	size_t bootsize, bytes;
+	ssize_t bootsize;
 	int bootfd;
 
 	/*
@@ -402,12 +403,18 @@
 	}
 		
 	bootsize = lseek(bootfd, 0, SEEK_END);
-	boot = malloc(bootsize);
-	lseek(bootfd, 0, SEEK_SET);
-	bytes = 0;
-	while (bytes < bootsize)
-		bytes += read(bootfd, boot + bytes, bootsize - bytes);
-	close(bootfd);
+	if (bootsize == -1) {
+		dialog_msgbox("Bootcode Error", strerror(errno), 0, 0,
+		    TRUE);
+		return;
+	}
+
+	boot = mmap(0, bootsize, PROT_READ, 0, bootfd, 0);
+	if (boot == MAP_FAILED) {
+		dialog_msgbox("Bootcode Error", strerror(errno), 0, 0,
+		    TRUE);
+		return;
+	}
 
 	r = gctl_get_handle();
 	gctl_ro_param(r, "class", -1, "PART");
@@ -419,7 +426,8 @@
 	if (errstr != NULL && errstr[0] != '\0') 
 		gpart_show_error("Bootcode Error", NULL, errstr);
 	gctl_free(r);
-	free(boot);
+	munmap(boot, bootsize);
+	close(bootfd);
 }
 
 static void