1 files changed, 71 insertions, 89 deletions

diff --git a/arch/i386/boot/tools/build.c b/arch/i386/boot/tools/build.c
index 05798419a6a9..886f47d8a488 100644
--- a/arch/i386/boot/tools/build.c
+++ b/arch/i386/boot/tools/build.c
@@ -1,13 +1,12 @@
 /*
  *  Copyright (C) 1991, 1992  Linus Torvalds
  *  Copyright (C) 1997 Martin Mares
+ *  Copyright (C) 2007 H. Peter Anvin
  */
 
 /*
  * This file builds a disk-image from three different files:
  *
- * - bootsect: compatibility mbr which prints an error message if
- *             someone tries to boot the kernel directly.
  * - setup: 8086 machine code, sets up system parm
  * - system: 80386 code for actual system
  *
@@ -21,6 +20,7 @@
  * High loaded stuff by Hans Lermen & Werner Almesberger, Feb. 1996
  * Cross compiling fixes by Gertjan van Wingerde, July 1996
  * Rewritten by Martin Mares, April 1997
+ * Substantially overhauled by H. Peter Anvin, April 2007
  */
 
 #include <stdio.h>
@@ -32,23 +32,25 @@
 #include <sys/sysmacros.h>
 #include <unistd.h>
 #include <fcntl.h>
+#include <sys/mman.h>
 #include <asm/boot.h>
 
-typedef unsigned char byte;
-typedef unsigned short word;
-typedef unsigned long u32;
+typedef unsigned char  u8;
+typedef unsigned short u16;
+typedef unsigned long  u32;
 
 #define DEFAULT_MAJOR_ROOT 0
 #define DEFAULT_MINOR_ROOT 0
 
-/* Minimal number of setup sectors (see also bootsect.S) */
-#define SETUP_SECTS 4
+/* Minimal number of setup sectors */
+#define SETUP_SECT_MIN 5
+#define SETUP_SECT_MAX 64
 
-byte buf[1024];
-int fd;
+/* This must be large enough to hold the entire setup */
+u8 buf[SETUP_SECT_MAX*512];
 int is_big_kernel;
 
-void die(const char * str, ...)
+static void die(const char * str, ...)
 {
         va_list args;
         va_start(args, str);
@@ -57,15 +59,9 @@ void die(const char * str, ...)
         exit(1);
 }
 
-void file_open(const char *name)
+static void usage(void)
 {
-        if ((fd = open(name, O_RDONLY, 0)) < 0)
-                die("Unable to open `%s': %m", name);
-}
-
-void usage(void)
-{
-        die("Usage: build [-b] bootsect setup system [rootdev] [> image]");
+        die("Usage: build [-b] setup system [rootdev] [> image]");
 }
 
 int main(int argc, char ** argv)
@@ -73,27 +69,30 @@ int main(int argc, char ** argv)
         unsigned int i, sz, setup_sectors;
         int c;
         u32 sys_size;
-        byte major_root, minor_root;
+        u8 major_root, minor_root;
         struct stat sb;
+        FILE *file;
+        int fd;
+        void *kernel;
 
         if (argc > 2 && !strcmp(argv[1], "-b"))
           {
             is_big_kernel = 1;
             argc--, argv++;
           }
-        if ((argc < 4) || (argc > 5))
+        if ((argc < 3) || (argc > 4))
                 usage();
-        if (argc > 4) {
-                if (!strcmp(argv[4], "CURRENT")) {
+        if (argc > 3) {
+                if (!strcmp(argv[3], "CURRENT")) {
                         if (stat("/", &sb)) {
                                 perror("/");
                                 die("Couldn't stat /");
                         }
                         major_root = major(sb.st_dev);
                         minor_root = minor(sb.st_dev);
-                } else if (strcmp(argv[4], "FLOPPY")) {
-                        if (stat(argv[4], &sb)) {
-                                perror(argv[4]);
+                } else if (strcmp(argv[3], "FLOPPY")) {
+                        if (stat(argv[3], &sb)) {
+                                perror(argv[3]);
                                 die("Couldn't stat root device.");
                         }
                         major_root = major(sb.st_rdev);
@@ -108,79 +107,62 @@ int main(int argc, char ** argv)
         }
         fprintf(stderr, "Root device is (%d, %d)\n", major_root, minor_root);
 
-        file_open(argv[1]);
-        i = read(fd, buf, sizeof(buf));
-        fprintf(stderr,"Boot sector %d bytes.\n",i);
-        if (i != 512)
-                die("Boot block must be exactly 512 bytes");
+        /* Copy the setup code */
+        file = fopen(argv[1], "r");
+        if (!file)
+                die("Unable to open `%s': %m", argv[1]);
+        c = fread(buf, 1, sizeof(buf), file);
+        if (ferror(file))
+                die("read-error on `setup'");
+        if (c < 1024)
+                die("The setup must be at least 1024 bytes");
         if (buf[510] != 0x55 || buf[511] != 0xaa)
                 die("Boot block hasn't got boot flag (0xAA55)");
+        fclose(file);
+
+        /* Pad unused space with zeros */
+        setup_sectors = (c + 511) / 512;
+        if (setup_sectors < SETUP_SECT_MIN)
+                setup_sectors = SETUP_SECT_MIN;
+        i = setup_sectors*512;
+        memset(buf+c, 0, i-c);
+
+        /* Set the default root device */
         buf[508] = minor_root;
         buf[509] = major_root;
-        if (write(1, buf, 512) != 512)
-                die("Write call failed");
-        close (fd);
-
-        file_open(argv[2]);                                 /* Copy the setup code */
-        for (i=0 ; (c=read(fd, buf, sizeof(buf)))>0 ; i+=c )
-                if (write(1, buf, c) != c)
-                        die("Write call failed");
-        if (c != 0)
-                die("read-error on `setup'");
-        close (fd);
-
-        setup_sectors = (i + 511) / 512;        /* Pad unused space with zeros */
-        /* for compatibility with ancient versions of LILO. */
-        if (setup_sectors < SETUP_SECTS)
-                setup_sectors = SETUP_SECTS;
-        fprintf(stderr, "Setup is %d bytes.\n", i);
-        memset(buf, 0, sizeof(buf));
-        while (i < setup_sectors * 512) {
-                c = setup_sectors * 512 - i;
-                if (c > sizeof(buf))
-                        c = sizeof(buf);
-                if (write(1, buf, c) != c)
-                        die("Write call failed");
-                i += c;
-        }
 
-        file_open(argv[3]);
-        if (fstat (fd, &sb))
-                die("Unable to stat `%s': %m", argv[3]);
+        fprintf(stderr, "Setup is %d bytes (padded to %d bytes).\n", c, i);
+
+        /* Open and stat the kernel file */
+        fd = open(argv[2], O_RDONLY);
+        if (fd < 0)
+                die("Unable to open `%s': %m", argv[2]);
+        if (fstat(fd, &sb))
+                die("Unable to stat `%s': %m", argv[2]);
         sz = sb.st_size;
-        fprintf (stderr, "System is %d kB\n", sz/1024);
+        fprintf (stderr, "System is %d kB\n", (sz+1023)/1024);
+        kernel = mmap(NULL, sz, PROT_READ, MAP_SHARED, fd, 0);
+        if (kernel == MAP_FAILED)
+                die("Unable to mmap '%s': %m", argv[2]);
         sys_size = (sz + 15) / 16;
         if (!is_big_kernel && sys_size > DEF_SYSSIZE)
                 die("System is too big. Try using bzImage or modules.");
-        while (sz > 0) {
-                int l, n;
-
-                l = (sz > sizeof(buf)) ? sizeof(buf) : sz;
-                if ((n=read(fd, buf, l)) != l) {
-                        if (n < 0)
-                                die("Error reading %s: %m", argv[3]);
-                        else
-                                die("%s: Unexpected EOF", argv[3]);
-                }
-                if (write(1, buf, l) != l)
-                        die("Write failed");
-                sz -= l;
-        }
+
+        /* Patch the setup code with the appropriate size parameters */
+        buf[0x1f1] = setup_sectors-1;
+        buf[0x1f4] = sys_size;
+        buf[0x1f5] = sys_size >> 8;
+        buf[0x1f6] = sys_size >> 16;
+        buf[0x1f7] = sys_size >> 24;
+
+        if (fwrite(buf, 1, i, stdout) != i)
+                die("Writing setup failed");
+
+        /* Copy the kernel code */
+        if (fwrite(kernel, 1, sz, stdout) != sz)
+                die("Writing kernel failed");
         close(fd);
 
-        if (lseek(1, 497, SEEK_SET) != 497)                 /* Write sizes to the bootsector */
-                die("Output: seek failed");
-        buf[0] = setup_sectors;
-        if (write(1, buf, 1) != 1)
-                die("Write of setup sector count failed");
-        if (lseek(1, 500, SEEK_SET) != 500)
-                die("Output: seek failed");
-        buf[0] = (sys_size & 0xff);
-        buf[1] = ((sys_size >> 8) & 0xff);
-        buf[2] = ((sys_size >> 16) & 0xff);
-        buf[3] = ((sys_size >> 24) & 0xff);
-        if (write(1, buf, 4) != 4)
-                die("Write of image length failed");
-
-        return 0;                                           /* Everything is OK */
+        /* Everything is OK */
+        return 0;
 }