cregit-Linux how code gets into the kernel

Release 4.14 arch/mn10300/boot/tools/build.c

// SPDX-License-Identifier: GPL-2.0
/*
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *  Copyright (C) 1997 Martin Mares
 */

/*
 * This file builds a disk-image from three different files:
 *
 * - bootsect: exactly 512 bytes of 8086 machine code, loads the rest
 * - setup: 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
 * 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
 */

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <stdarg.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/sysmacros.h>
#include <unistd.h>
#include <fcntl.h>
#include <asm/boot.h>


#define DEFAULT_MAJOR_ROOT 0

#define DEFAULT_MINOR_ROOT 0

/* Minimal number of setup sectors (see also bootsect.S) */

#define SETUP_SECTS 4


uint8_t buf[1024];

int fd;

int is_big_kernel;

__attribute__((noreturn))

void die(const char *str, ...) { va_list args; va_start(args, str); vfprintf(stderr, str, args); fputc('\n', stderr); exit(1); }

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David Howells43100.00%1100.00%
Total43100.00%1100.00%


void file_open(const char *name) { fd = open(name, O_RDONLY, 0); if (fd < 0) die("Unable to open `%s': %m", name); }

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__attribute__((noreturn))
void usage(void) { die("Usage: build [-b] bootsect setup system [rootdev] [> image]"); }

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int main(int argc, char **argv) { unsigned int i, c, sz, setup_sectors; uint32_t sys_size; uint8_t major_root, minor_root; struct stat sb; if (argc > 2 && !strcmp(argv[1], "-b")) { is_big_kernel = 1; argc--, argv++; } if ((argc < 4) || (argc > 5)) usage(); if (argc > 4) { if (!strcmp(argv[4], "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]); 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); 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"); if (buf[510] != 0x55 || buf[511] != 0xaa) die("Boot block hasn't got boot flag (0xAA55)"); buf[508] = minor_root; buf[509] = major_root; if (write(1, buf, 512) != 512) die("Write call failed"); close(fd); /* Copy the setup code */ file_open(argv[2]); 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); /* Pad unused space with zeros */ setup_sectors = (i + 511) / 512; /* 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]); sz = sb.st_size; fprintf(stderr, "System is %d kB\n", sz / 1024); sys_size = (sz + 15) / 16; /* 0x28000*16 = 2.5 MB, conservative estimate for the current maximum */ if (sys_size > (is_big_kernel ? 0x28000 : DEF_SYSSIZE)) die("System is too big. Try using %smodules.", is_big_kernel ? "" : "bzImage or "); if (sys_size > 0xffff) fprintf(stderr, "warning: kernel is too big for standalone boot " "from floppy\n"); while (sz > 0) { int l, n; l = (sz > sizeof(buf)) ? sizeof(buf) : sz; n = read(fd, buf, l); if (n != 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; } close(fd); /* Write sizes to the bootsector */ if (lseek(1, 497, SEEK_SET) != 497) 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); if (write(1, buf, 2) != 2) die("Write of image length failed"); return 0; }

Contributors

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David Howells814100.00%1100.00%
Total814100.00%1100.00%


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David Howells96999.90%150.00%
Greg Kroah-Hartman10.10%150.00%
Total970100.00%2100.00%
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