1 // SPDX-License-Identifier: GPL-2.0-only 2 /* -*- linux-c -*- ------------------------------------------------------- * 3 * 4 * Copyright (C) 1991, 1992 Linus Torvalds 5 * Copyright 2007 rPath, Inc. - All Rights Reserved 6 * Copyright 2009 Intel Corporation; author H. Peter Anvin 7 * 8 * ----------------------------------------------------------------------- */ 9 10 /* 11 * Main module for the real-mode kernel code 12 */ 13 14 #include "boot.h" 15 #include "string.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 * Query the keyboard lock status as given by the BIOS, and 60 * set the keyboard repeat rate to maximum. Unclear why the latter 61 * is done here; this might be possible to kill off as stale code. 62 */ 63 static void keyboard_init(void) 64 { 65 struct biosregs ireg, oreg; 66 initregs(&ireg); 67 68 ireg.ah = 0x02; /* Get keyboard status */ 69 intcall(0x16, &ireg, &oreg); 70 boot_params.kbd_status = oreg.al; 71 72 ireg.ax = 0x0305; /* Set keyboard repeat rate */ 73 intcall(0x16, &ireg, NULL); 74 } 75 76 /* 77 * Get Intel SpeedStep (IST) information. 78 */ 79 static void query_ist(void) 80 { 81 struct biosregs ireg, oreg; 82 83 /* Some older BIOSes apparently crash on this call, so filter 84 it from machines too old to have SpeedStep at all. */ 85 if (cpu.level < 6) 86 return; 87 88 initregs(&ireg); 89 ireg.ax = 0xe980; /* IST Support */ 90 ireg.edx = 0x47534943; /* Request value */ 91 intcall(0x15, &ireg, &oreg); 92 93 boot_params.ist_info.signature = oreg.eax; 94 boot_params.ist_info.command = oreg.ebx; 95 boot_params.ist_info.event = oreg.ecx; 96 boot_params.ist_info.perf_level = oreg.edx; 97 } 98 99 /* 100 * Tell the BIOS what CPU mode we intend to run in. 101 */ 102 static void set_bios_mode(void) 103 { 104 #ifdef CONFIG_X86_64 105 struct biosregs ireg; 106 107 initregs(&ireg); 108 ireg.ax = 0xec00; 109 ireg.bx = 2; 110 intcall(0x15, &ireg, NULL); 111 #endif 112 } 113 114 static void init_heap(void) 115 { 116 char *stack_end; 117 118 if (boot_params.hdr.loadflags & CAN_USE_HEAP) { 119 asm("leal %P1(%%esp),%0" 120 : "=r" (stack_end) : "i" (-STACK_SIZE)); 121 122 heap_end = (char *) 123 ((size_t)boot_params.hdr.heap_end_ptr + 0x200); 124 if (heap_end > stack_end) 125 heap_end = stack_end; 126 } else { 127 /* Boot protocol 2.00 only, no heap available */ 128 puts("WARNING: Ancient bootloader, some functionality " 129 "may be limited!\n"); 130 } 131 } 132 133 void main(void) 134 { 135 /* First, copy the boot header into the "zeropage" */ 136 copy_boot_params(); 137 138 /* Initialize the early-boot console */ 139 console_init(); 140 if (cmdline_find_option_bool("debug")) 141 puts("early console in setup code\n"); 142 143 /* End of heap check */ 144 init_heap(); 145 146 /* Make sure we have all the proper CPU support */ 147 if (validate_cpu()) { 148 puts("Unable to boot - please use a kernel appropriate " 149 "for your CPU.\n"); 150 die(); 151 } 152 153 /* Tell the BIOS what CPU mode we intend to run in. */ 154 set_bios_mode(); 155 156 /* Detect memory layout */ 157 detect_memory(); 158 159 /* Set keyboard repeat rate (why?) and query the lock flags */ 160 keyboard_init(); 161 162 /* Query Intel SpeedStep (IST) information */ 163 query_ist(); 164 165 /* Query APM information */ 166 #if defined(CONFIG_APM) || defined(CONFIG_APM_MODULE) 167 query_apm_bios(); 168 #endif 169 170 /* Query EDD information */ 171 #if defined(CONFIG_EDD) || defined(CONFIG_EDD_MODULE) 172 query_edd(); 173 #endif 174 175 /* Set the video mode */ 176 set_video(); 177 178 /* Do the last things and invoke protected mode */ 179 go_to_protected_mode(); 180 } 181