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kernel/linux-imx6_3.14.28/arch/x86/boot/main.c 4.33 KB
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  /* -*- linux-c -*- ------------------------------------------------------- *
   *
   *   Copyright (C) 1991, 1992 Linus Torvalds
   *   Copyright 2007 rPath, Inc. - All Rights Reserved
   *   Copyright 2009 Intel Corporation; author H. Peter Anvin
   *
   *   This file is part of the Linux kernel, and is made available under
   *   the terms of the GNU General Public License version 2.
   *
   * ----------------------------------------------------------------------- */
  
  /*
   * Main module for the real-mode kernel code
   */
  
  #include "boot.h"
  
  struct boot_params boot_params __attribute__((aligned(16)));
  
  char *HEAP = _end;
  char *heap_end = _end;		/* Default end of heap = no heap */
  
  /*
   * Copy the header into the boot parameter block.  Since this
   * screws up the old-style command line protocol, adjust by
   * filling in the new-style command line pointer instead.
   */
  
  static void copy_boot_params(void)
  {
  	struct old_cmdline {
  		u16 cl_magic;
  		u16 cl_offset;
  	};
  	const struct old_cmdline * const oldcmd =
  		(const struct old_cmdline *)OLD_CL_ADDRESS;
  
  	BUILD_BUG_ON(sizeof boot_params != 4096);
  	memcpy(&boot_params.hdr, &hdr, sizeof hdr);
  
  	if (!boot_params.hdr.cmd_line_ptr &&
  	    oldcmd->cl_magic == OLD_CL_MAGIC) {
  		/* Old-style command line protocol. */
  		u16 cmdline_seg;
  
  		/* Figure out if the command line falls in the region
  		   of memory that an old kernel would have copied up
  		   to 0x90000... */
  		if (oldcmd->cl_offset < boot_params.hdr.setup_move_size)
  			cmdline_seg = ds();
  		else
  			cmdline_seg = 0x9000;
  
  		boot_params.hdr.cmd_line_ptr =
  			(cmdline_seg << 4) + oldcmd->cl_offset;
  	}
  }
  
  /*
   * Query the keyboard lock status as given by the BIOS, and
   * set the keyboard repeat rate to maximum.  Unclear why the latter
   * is done here; this might be possible to kill off as stale code.
   */
  static void keyboard_init(void)
  {
  	struct biosregs ireg, oreg;
  	initregs(&ireg);
  
  	ireg.ah = 0x02;		/* Get keyboard status */
  	intcall(0x16, &ireg, &oreg);
  	boot_params.kbd_status = oreg.al;
  
  	ireg.ax = 0x0305;	/* Set keyboard repeat rate */
  	intcall(0x16, &ireg, NULL);
  }
  
  /*
   * Get Intel SpeedStep (IST) information.
   */
  static void query_ist(void)
  {
  	struct biosregs ireg, oreg;
  
  	/* Some older BIOSes apparently crash on this call, so filter
  	   it from machines too old to have SpeedStep at all. */
  	if (cpu.level < 6)
  		return;
  
  	initregs(&ireg);
  	ireg.ax  = 0xe980;	 /* IST Support */
  	ireg.edx = 0x47534943;	 /* Request value */
  	intcall(0x15, &ireg, &oreg);
  
  	boot_params.ist_info.signature  = oreg.eax;
  	boot_params.ist_info.command    = oreg.ebx;
  	boot_params.ist_info.event      = oreg.ecx;
  	boot_params.ist_info.perf_level = oreg.edx;
  }
  
  /*
   * Tell the BIOS what CPU mode we intend to run in.
   */
  static void set_bios_mode(void)
  {
  #ifdef CONFIG_X86_64
  	struct biosregs ireg;
  
  	initregs(&ireg);
  	ireg.ax = 0xec00;
  	ireg.bx = 2;
  	intcall(0x15, &ireg, NULL);
  #endif
  }
  
  static void init_heap(void)
  {
  	char *stack_end;
  
  	if (boot_params.hdr.loadflags & CAN_USE_HEAP) {
  		asm("leal %P1(%%esp),%0"
  		    : "=r" (stack_end) : "i" (-STACK_SIZE));
  
  		heap_end = (char *)
  			((size_t)boot_params.hdr.heap_end_ptr + 0x200);
  		if (heap_end > stack_end)
  			heap_end = stack_end;
  	} else {
  		/* Boot protocol 2.00 only, no heap available */
  		puts("WARNING: Ancient bootloader, some functionality "
  		     "may be limited!
  ");
  	}
  }
  
  void main(void)
  {
  	/* First, copy the boot header into the "zeropage" */
  	copy_boot_params();
  
  	/* Initialize the early-boot console */
  	console_init();
  	if (cmdline_find_option_bool("debug"))
  		puts("early console in setup code
  ");
  
  	/* End of heap check */
  	init_heap();
  
  	/* Make sure we have all the proper CPU support */
  	if (validate_cpu()) {
  		puts("Unable to boot - please use a kernel appropriate "
  		     "for your CPU.
  ");
  		die();
  	}
  
  	/* Tell the BIOS what CPU mode we intend to run in. */
  	set_bios_mode();
  
  	/* Detect memory layout */
  	detect_memory();
  
  	/* Set keyboard repeat rate (why?) and query the lock flags */
  	keyboard_init();
  
  	/* Query MCA information */
  	query_mca();
  
  	/* Query Intel SpeedStep (IST) information */
  	query_ist();
  
  	/* Query APM information */
  #if defined(CONFIG_APM) || defined(CONFIG_APM_MODULE)
  	query_apm_bios();
  #endif
  
  	/* Query EDD information */
  #if defined(CONFIG_EDD) || defined(CONFIG_EDD_MODULE)
  	query_edd();
  #endif
  
  	/* Set the video mode */
  	set_video();
  
  	/* Do the last things and invoke protected mode */
  	go_to_protected_mode();
  }