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#include <linux/build_bug.h> 14 15#include "boot.h" 16#include "string.h" 17 18struct boot_params boot_params __attribute__((aligned(16))); 19 20char *HEAP = _end; 21char *heap_end = _end; /* Default end of heap = no heap */ 22 23/* 24 * Copy the header into the boot parameter block. Since this 25 * screws up the old-style command line protocol, adjust by 26 * filling in the new-style command line pointer instead. 27 */ 28 29static void copy_boot_params(void) 30{ 31 struct old_cmdline { 32 u16 cl_magic; 33 u16 cl_offset; 34 }; 35 const struct old_cmdline * const oldcmd = 36 absolute_pointer(OLD_CL_ADDRESS); 37 38 BUILD_BUG_ON(sizeof(boot_params) != 4096); 39 memcpy(&boot_params.hdr, &hdr, sizeof(hdr)); 40 41 if (!boot_params.hdr.cmd_line_ptr && 42 oldcmd->cl_magic == OLD_CL_MAGIC) { 43 /* Old-style command line protocol. */ 44 u16 cmdline_seg; 45 46 /* Figure out if the command line falls in the region 47 of memory that an old kernel would have copied up 48 to 0x90000... */ 49 if (oldcmd->cl_offset < boot_params.hdr.setup_move_size) 50 cmdline_seg = ds(); 51 else 52 cmdline_seg = 0x9000; 53 54 boot_params.hdr.cmd_line_ptr = 55 (cmdline_seg << 4) + oldcmd->cl_offset; 56 } 57} 58 59/* 60 * Query the keyboard lock status as given by the BIOS, and 61 * set the keyboard repeat rate to maximum. Unclear why the latter 62 * is done here; this might be possible to kill off as stale code. 63 */ 64static void keyboard_init(void) 65{ 66 struct biosregs ireg, oreg; 67 initregs(&ireg); 68 69 ireg.ah = 0x02; /* Get keyboard status */ 70 intcall(0x16, &ireg, &oreg); 71 boot_params.kbd_status = oreg.al; 72 73 ireg.ax = 0x0305; /* Set keyboard repeat rate */ 74 intcall(0x16, &ireg, NULL); 75} 76 77/* 78 * Get Intel SpeedStep (IST) information. 79 */ 80static void query_ist(void) 81{ 82 struct biosregs ireg, oreg; 83 84 /* Some older BIOSes apparently crash on this call, so filter 85 it from machines too old to have SpeedStep at all. */ 86 if (cpu.level < 6) 87 return; 88 89 initregs(&ireg); 90 ireg.ax = 0xe980; /* IST Support */ 91 ireg.edx = 0x47534943; /* Request value */ 92 intcall(0x15, &ireg, &oreg); 93 94 boot_params.ist_info.signature = oreg.eax; 95 boot_params.ist_info.command = oreg.ebx; 96 boot_params.ist_info.event = oreg.ecx; 97 boot_params.ist_info.perf_level = oreg.edx; 98} 99 100/* 101 * Tell the BIOS what CPU mode we intend to run in. 102 */ 103static void set_bios_mode(void) 104{ 105#ifdef CONFIG_X86_64 106 struct biosregs ireg; 107 108 initregs(&ireg); 109 ireg.ax = 0xec00; 110 ireg.bx = 2; 111 intcall(0x15, &ireg, NULL); 112#endif 113} 114 115static void init_heap(void) 116{ 117 char *stack_end; 118 119 if (boot_params.hdr.loadflags & CAN_USE_HEAP) { 120 asm("leal %P1(%%esp),%0" 121 : "=r" (stack_end) : "i" (-STACK_SIZE)); 122 123 heap_end = (char *) 124 ((size_t)boot_params.hdr.heap_end_ptr + 0x200); 125 if (heap_end > stack_end) 126 heap_end = stack_end; 127 } else { 128 /* Boot protocol 2.00 only, no heap available */ 129 puts("WARNING: Ancient bootloader, some functionality " 130 "may be limited!\n"); 131 } 132} 133 134void main(void) 135{ 136 /* First, copy the boot header into the "zeropage" */ 137 copy_boot_params(); 138 139 /* Initialize the early-boot console */ 140 console_init(); 141 if (cmdline_find_option_bool("debug")) 142 puts("early console in setup code\n"); 143 144 /* End of heap check */ 145 init_heap(); 146 147 /* Make sure we have all the proper CPU support */ 148 if (validate_cpu()) { 149 puts("Unable to boot - please use a kernel appropriate " 150 "for your CPU.\n"); 151 die(); 152 } 153 154 /* Tell the BIOS what CPU mode we intend to run in. */ 155 set_bios_mode(); 156 157 /* Detect memory layout */ 158 detect_memory(); 159 160 /* Set keyboard repeat rate (why?) and query the lock flags */ 161 keyboard_init(); 162 163 /* Query Intel SpeedStep (IST) information */ 164 query_ist(); 165 166 /* Query APM information */ 167#if defined(CONFIG_APM) || defined(CONFIG_APM_MODULE) 168 query_apm_bios(); 169#endif 170 171 /* Query EDD information */ 172#if defined(CONFIG_EDD) || defined(CONFIG_EDD_MODULE) 173 query_edd(); 174#endif 175 176 /* Set the video mode */ 177 set_video(); 178 179 /* Do the last things and invoke protected mode */ 180 go_to_protected_mode(); 181} 182