1 /* -*- linux-c -*- ------------------------------------------------------- * 2 * 3 * Copyright (C) 1991, 1992 Linus Torvalds 4 * Copyright 2007 rPath, Inc. - All Rights Reserved 5 * 6 * This file is part of the Linux kernel, and is made available under 7 * the terms of the GNU General Public License version 2. 8 * 9 * ----------------------------------------------------------------------- */ 10 11 /* 12 * Main module for the real-mode kernel code 13 */ 14 15 #include "boot.h" 16 17 struct boot_params boot_params __attribute__((aligned(16))); 18 19 char *HEAP = _end; 20 char *heap_end = _end; /* Default end of heap = no heap */ 21 22 /* 23 * Copy the header into the boot parameter block. Since this 24 * screws up the old-style command line protocol, adjust by 25 * filling in the new-style command line pointer instead. 26 */ 27 28 static void copy_boot_params(void) 29 { 30 struct old_cmdline { 31 u16 cl_magic; 32 u16 cl_offset; 33 }; 34 const struct old_cmdline * const oldcmd = 35 (const struct old_cmdline *)OLD_CL_ADDRESS; 36 37 BUILD_BUG_ON(sizeof boot_params != 4096); 38 memcpy(&boot_params.hdr, &hdr, sizeof hdr); 39 40 if (!boot_params.hdr.cmd_line_ptr && 41 oldcmd->cl_magic == OLD_CL_MAGIC) { 42 /* Old-style command line protocol. */ 43 u16 cmdline_seg; 44 45 /* Figure out if the command line falls in the region 46 of memory that an old kernel would have copied up 47 to 0x90000... */ 48 if (oldcmd->cl_offset < boot_params.hdr.setup_move_size) 49 cmdline_seg = ds(); 50 else 51 cmdline_seg = 0x9000; 52 53 boot_params.hdr.cmd_line_ptr = 54 (cmdline_seg << 4) + oldcmd->cl_offset; 55 } 56 } 57 58 /* 59 * Set the keyboard repeat rate to maximum. Unclear why this 60 * is done here; this might be possible to kill off as stale code. 61 */ 62 static void keyboard_set_repeat(void) 63 { 64 u16 ax = 0x0305; 65 u16 bx = 0; 66 asm volatile("int $0x16" 67 : "+a" (ax), "+b" (bx) 68 : : "ecx", "edx", "esi", "edi"); 69 } 70 71 /* 72 * Get Intel SpeedStep (IST) information. 73 */ 74 static void query_ist(void) 75 { 76 /* Some older BIOSes apparently crash on this call, so filter 77 it from machines too old to have SpeedStep at all. */ 78 if (cpu.level < 6) 79 return; 80 81 asm("int $0x15" 82 : "=a" (boot_params.ist_info.signature), 83 "=b" (boot_params.ist_info.command), 84 "=c" (boot_params.ist_info.event), 85 "=d" (boot_params.ist_info.perf_level) 86 : "a" (0x0000e980), /* IST Support */ 87 "d" (0x47534943)); /* Request value */ 88 } 89 90 /* 91 * Tell the BIOS what CPU mode we intend to run in. 92 */ 93 static void set_bios_mode(void) 94 { 95 #ifdef CONFIG_X86_64 96 u32 eax, ebx; 97 98 eax = 0xec00; 99 ebx = 2; 100 asm volatile("int $0x15" 101 : "+a" (eax), "+b" (ebx) 102 : : "ecx", "edx", "esi", "edi"); 103 #endif 104 } 105 106 static void init_heap(void) 107 { 108 char *stack_end; 109 110 if (boot_params.hdr.loadflags & CAN_USE_HEAP) { 111 asm("leal %P1(%%esp),%0" 112 : "=r" (stack_end) : "i" (-STACK_SIZE)); 113 114 heap_end = (char *) 115 ((size_t)boot_params.hdr.heap_end_ptr + 0x200); 116 if (heap_end > stack_end) 117 heap_end = stack_end; 118 } else { 119 /* Boot protocol 2.00 only, no heap available */ 120 puts("WARNING: Ancient bootloader, some functionality " 121 "may be limited!\n"); 122 } 123 } 124 125 void main(void) 126 { 127 /* First, copy the boot header into the "zeropage" */ 128 copy_boot_params(); 129 130 /* End of heap check */ 131 init_heap(); 132 133 /* Make sure we have all the proper CPU support */ 134 if (validate_cpu()) { 135 puts("Unable to boot - please use a kernel appropriate " 136 "for your CPU.\n"); 137 die(); 138 } 139 140 /* Tell the BIOS what CPU mode we intend to run in. */ 141 set_bios_mode(); 142 143 /* Detect memory layout */ 144 detect_memory(); 145 146 /* Set keyboard repeat rate (why?) */ 147 keyboard_set_repeat(); 148 149 /* Query MCA information */ 150 query_mca(); 151 152 /* Query Intel SpeedStep (IST) information */ 153 query_ist(); 154 155 /* Query APM information */ 156 #if defined(CONFIG_APM) || defined(CONFIG_APM_MODULE) 157 query_apm_bios(); 158 #endif 159 160 /* Query EDD information */ 161 #if defined(CONFIG_EDD) || defined(CONFIG_EDD_MODULE) 162 query_edd(); 163 #endif 164 165 /* Set the video mode */ 166 set_video(); 167 168 /* Parse command line for 'quiet' and pass it to decompressor. */ 169 if (cmdline_find_option_bool("quiet")) 170 boot_params.hdr.loadflags |= QUIET_FLAG; 171 172 /* Do the last things and invoke protected mode */ 173 go_to_protected_mode(); 174 } 175