| // SPDX-License-Identifier: GPL-2.0-only |
| /* -*- linux-c -*- ------------------------------------------------------- * |
| * |
| * Copyright (C) 1991, 1992 Linus Torvalds |
| * Copyright 2007 rPath, Inc. - All Rights Reserved |
| * Copyright 2009 Intel Corporation; author H. Peter Anvin |
| * |
| * ----------------------------------------------------------------------- */ |
| |
| /* |
| * Main module for the real-mode kernel code |
| */ |
| #include <linux/build_bug.h> |
| |
| #include "boot.h" |
| #include "string.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 = |
| absolute_pointer(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!\n"); |
| } |
| } |
| |
| 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\n"); |
| |
| /* 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.\n"); |
| 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 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(); |
| } |