mirror of https://gitee.com/openkylin/linux.git
191 lines
4.6 KiB
C
191 lines
4.6 KiB
C
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/*
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* Copyright (C) 1991, 1992 Linus Torvalds
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* Copyright (C) 1997 Martin Mares
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*/
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/*
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* This file builds a disk-image from three different files:
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*
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* - bootsect: exactly 512 bytes of 8086 machine code, loads the rest
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* - setup: 8086 machine code, sets up system parm
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* - system: 80386 code for actual system
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*
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* It does some checking that all files are of the correct type, and
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* just writes the result to stdout, removing headers and padding to
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* the right amount. It also writes some system data to stderr.
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*/
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/*
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* Changes by tytso to allow root device specification
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* High loaded stuff by Hans Lermen & Werner Almesberger, Feb. 1996
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* Cross compiling fixes by Gertjan van Wingerde, July 1996
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* Rewritten by Martin Mares, April 1997
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*/
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#include <stdio.h>
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#include <string.h>
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#include <stdlib.h>
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#include <stdarg.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <sys/sysmacros.h>
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#include <unistd.h>
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#include <fcntl.h>
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#include <asm/boot.h>
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#define DEFAULT_MAJOR_ROOT 0
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#define DEFAULT_MINOR_ROOT 0
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/* Minimal number of setup sectors (see also bootsect.S) */
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#define SETUP_SECTS 4
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uint8_t buf[1024];
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int fd;
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int is_big_kernel;
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__attribute__((noreturn))
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void die(const char *str, ...)
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{
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va_list args;
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va_start(args, str);
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vfprintf(stderr, str, args);
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fputc('\n', stderr);
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exit(1);
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}
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void file_open(const char *name)
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{
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fd = open(name, O_RDONLY, 0);
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if (fd < 0)
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die("Unable to open `%s': %m", name);
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}
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__attribute__((noreturn))
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void usage(void)
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{
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die("Usage: build [-b] bootsect setup system [rootdev] [> image]");
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}
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int main(int argc, char **argv)
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{
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unsigned int i, c, sz, setup_sectors;
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uint32_t sys_size;
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uint8_t major_root, minor_root;
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struct stat sb;
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if (argc > 2 && !strcmp(argv[1], "-b")) {
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is_big_kernel = 1;
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argc--, argv++;
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}
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if ((argc < 4) || (argc > 5))
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usage();
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if (argc > 4) {
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if (!strcmp(argv[4], "CURRENT")) {
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if (stat("/", &sb)) {
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perror("/");
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die("Couldn't stat /");
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}
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major_root = major(sb.st_dev);
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minor_root = minor(sb.st_dev);
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} else if (strcmp(argv[4], "FLOPPY")) {
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if (stat(argv[4], &sb)) {
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perror(argv[4]);
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die("Couldn't stat root device.");
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}
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major_root = major(sb.st_rdev);
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minor_root = minor(sb.st_rdev);
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} else {
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major_root = 0;
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minor_root = 0;
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}
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} else {
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major_root = DEFAULT_MAJOR_ROOT;
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minor_root = DEFAULT_MINOR_ROOT;
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}
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fprintf(stderr, "Root device is (%d, %d)\n", major_root, minor_root);
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file_open(argv[1]);
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i = read(fd, buf, sizeof(buf));
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fprintf(stderr, "Boot sector %d bytes.\n", i);
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if (i != 512)
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die("Boot block must be exactly 512 bytes");
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if (buf[510] != 0x55 || buf[511] != 0xaa)
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die("Boot block hasn't got boot flag (0xAA55)");
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buf[508] = minor_root;
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buf[509] = major_root;
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if (write(1, buf, 512) != 512)
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die("Write call failed");
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close(fd);
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/* Copy the setup code */
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file_open(argv[2]);
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for (i = 0; (c = read(fd, buf, sizeof(buf))) > 0; i += c)
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if (write(1, buf, c) != c)
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die("Write call failed");
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if (c != 0)
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die("read-error on `setup'");
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close(fd);
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/* Pad unused space with zeros */
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setup_sectors = (i + 511) / 512;
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/* for compatibility with ancient versions of LILO. */
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if (setup_sectors < SETUP_SECTS)
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setup_sectors = SETUP_SECTS;
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fprintf(stderr, "Setup is %d bytes.\n", i);
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memset(buf, 0, sizeof(buf));
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while (i < setup_sectors * 512) {
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c = setup_sectors * 512 - i;
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if (c > sizeof(buf))
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c = sizeof(buf);
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if (write(1, buf, c) != c)
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die("Write call failed");
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i += c;
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}
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file_open(argv[3]);
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if (fstat(fd, &sb))
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die("Unable to stat `%s': %m", argv[3]);
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sz = sb.st_size;
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fprintf(stderr, "System is %d kB\n", sz / 1024);
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sys_size = (sz + 15) / 16;
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/* 0x28000*16 = 2.5 MB, conservative estimate for the current maximum */
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if (sys_size > (is_big_kernel ? 0x28000 : DEF_SYSSIZE))
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die("System is too big. Try using %smodules.",
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is_big_kernel ? "" : "bzImage or ");
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if (sys_size > 0xffff)
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fprintf(stderr,
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"warning: kernel is too big for standalone boot "
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"from floppy\n");
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while (sz > 0) {
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int l, n;
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l = (sz > sizeof(buf)) ? sizeof(buf) : sz;
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n = read(fd, buf, l);
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if (n != l) {
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if (n < 0)
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die("Error reading %s: %m", argv[3]);
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else
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die("%s: Unexpected EOF", argv[3]);
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}
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if (write(1, buf, l) != l)
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die("Write failed");
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sz -= l;
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}
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close(fd);
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/* Write sizes to the bootsector */
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if (lseek(1, 497, SEEK_SET) != 497)
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die("Output: seek failed");
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buf[0] = setup_sectors;
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if (write(1, buf, 1) != 1)
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die("Write of setup sector count failed");
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if (lseek(1, 500, SEEK_SET) != 500)
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die("Output: seek failed");
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buf[0] = (sys_size & 0xff);
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buf[1] = ((sys_size >> 8) & 0xff);
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if (write(1, buf, 2) != 2)
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die("Write of image length failed");
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return 0;
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}
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