diff --git a/cur/linux/tools/build.c b/cur/linux/tools/build.c
new file mode 100644
index 0000000..8b8c7ab
--- /dev/null
+++ b/cur/linux/tools/build.c
@@ -0,0 +1,171 @@
+/*
+ *  linux/tools/build.c
+ *
+ *  (C) 1991  Linus Torvalds
+ */
+
+/*
+ * This file builds a disk-image from three different files:
+ *
+ * - bootsect: max 510 bytes of 8086 machine code, loads the rest
+ * - setup: max 4 sectors of 8086 machine code, sets up system parm
+ * - system: 80386 code for actual system
+ *
+ * It does some checking that all files are of the correct type, and
+ * just writes the result to stdout, removing headers and padding to
+ * the right amount. It also writes some system data to stderr.
+ */
+
+/*
+ * Changes by tytso to allow root device specification
+ */
+
+#include <stdio.h>	/* fprintf */
+#include <string.h>
+#include <stdlib.h>	/* contains exit */
+#include <sys/types.h>	/* unistd.h needs this */
+#include <sys/stat.h>
+#include <linux/fs.h>
+#include <unistd.h>	/* contains read/write */
+#include <fcntl.h>
+
+#define MAJOR(a) (((unsigned)(a))>>8)
+#define MINOR(a) ((a)&0xff)
+
+#define MINIX_HEADER 32
+#define GCC_HEADER 0x80  /* 0x1000 */   /* by wyj */
+
+#define SYS_SIZE 0x3000
+
+#define DEFAULT_MAJOR_ROOT 0x03  //0x02     /* by wyj */
+#define DEFAULT_MINOR_ROOT 0x00  //0x1d
+
+/* max nr of sectors of setup: don't change unless you also change
+ * bootsect etc */
+#define SETUP_SECTS 4
+
+#define STRINGIFY(x) #x
+
+void die(char * str)
+{
+	fprintf(stderr,"%s\n",str);
+	exit(1);
+}
+
+void usage(void)
+{
+	die("Usage: build bootsect setup system [rootdev] [> image]");
+}
+
+int main(int argc, char ** argv)
+{
+	int i,c,id;
+	char buf[1024*4];        /* by wyj */
+	char major_root, minor_root;
+	struct stat sb;
+
+	if ((argc != 4) && (argc != 5))
+		usage();
+	if (argc == 5) {
+		if (strcmp(argv[4], "FLOPPY")) {
+			if (stat(argv[4], &sb)) {
+				perror(argv[4]);
+				die("Couldn't stat root device.");
+			}
+			major_root = MAJOR(sb.st_rdev);
+			minor_root = MINOR(sb.st_rdev);
+		} else {
+			major_root = 0;
+			minor_root = 0;
+		}
+	} else {
+		major_root = DEFAULT_MAJOR_ROOT;
+		minor_root = DEFAULT_MINOR_ROOT;
+	}
+	fprintf(stderr, "Root device is (%d, %d)\n", major_root, minor_root);
+	if ((major_root != 2) && (major_root != 3) &&
+	    (major_root != 0)) {
+		fprintf(stderr, "Illegal root device (major = %d)\n",
+			major_root);
+		die("Bad root device --- major #");
+	}
+	for (i=0;i<sizeof buf; i++) buf[i]=0;
+	if ((id=open(argv[1],O_RDONLY,0))<0)
+		die("Unable to open 'boot'");
+	if (read(id,buf,MINIX_HEADER) != MINIX_HEADER)
+		die("Unable to read header of 'boot'");
+	if (((long *) buf)[0]!=0x04100301)
+		die("Non-Minix header of 'boot'");
+	if (((long *) buf)[1]!=MINIX_HEADER)
+		die("Non-Minix header of 'boot'");
+	if (((long *) buf)[3]!=0)
+		die("Illegal data segment in 'boot'");
+	if (((long *) buf)[4]!=0)
+		die("Illegal bss in 'boot'");
+	if (((long *) buf)[5] != 0)
+		die("Non-Minix header of 'boot'");
+	if (((long *) buf)[7] != 0)
+		die("Illegal symbol table in 'boot'");
+	i=read(id,buf,sizeof buf);
+	fprintf(stderr,"Boot sector %d bytes.\n",i);
+	if (i != 512)
+		die("Boot block must be exactly 512 bytes");
+	if ((*(unsigned short *)(buf+510)) != 0xAA55)
+		die("Boot block hasn't got boot flag (0xAA55)");
+	buf[508] = (char) minor_root;
+	buf[509] = (char) major_root;	
+	i=write(1,buf,512);
+	if (i!=512)
+		die("Write call failed");
+	close (id);
+	
+	if ((id=open(argv[2],O_RDONLY,0))<0)
+		die("Unable to open 'setup'");
+	if (read(id,buf,MINIX_HEADER) != MINIX_HEADER)
+		die("Unable to read header of 'setup'");
+	if (((long *) buf)[0]!=0x04100301)
+		die("Non-Minix header of 'setup'");
+	if (((long *) buf)[1]!=MINIX_HEADER)
+		die("Non-Minix header of 'setup'");
+	if (((long *) buf)[3]!=0)
+		die("Illegal data segment in 'setup'");
+	if (((long *) buf)[4]!=0)
+		die("Illegal bss in 'setup'");
+	if (((long *) buf)[5] != 0)
+		die("Non-Minix header of 'setup'");
+	if (((long *) buf)[7] != 0)
+		die("Illegal symbol table in 'setup'");
+	for (i=0 ; (c=read(id,buf,sizeof buf))>0 ; i+=c )
+		if (write(1,buf,c)!=c)
+			die("Write call failed");
+	close (id);
+	if (i > SETUP_SECTS*512)
+		die("Setup exceeds " STRINGIFY(SETUP_SECTS)
+			" sectors - rewrite build/boot/setup");
+	fprintf(stderr,"Setup is %d bytes.\n",i);
+	for (c=0 ; c<sizeof(buf) ; c++)
+		buf[c] = '\0';
+	while (i<SETUP_SECTS*512) {
+		c = SETUP_SECTS*512-i;
+		if (c > sizeof(buf))
+			c = sizeof(buf);
+		if (write(1,buf,c) != c)
+			die("Write call failed");
+		i += c;
+	}
+	
+	if ((id=open(argv[3],O_RDONLY,0))<0)
+		die("Unable to open 'system'");
+	if (read(id,buf,GCC_HEADER) != GCC_HEADER)
+		die("Unable to read header of 'system'");
+//	if (((long *) buf)[5] != 0)
+//		die("Non-GCC header of 'system'");
+	for (i=0 ; (c=read(id,buf,sizeof buf))>0 ; i+=c )
+		if (write(1,buf,c)!=c)
+			die("Write call failed");
+	close(id);
+	fprintf(stderr,"System is %d bytes.\n",i);
+	if (i > SYS_SIZE*16)
+		die("System is too big");
+	return(0);
+}