diff options
Diffstat (limited to 'arch/x86/boot/main.c')
| -rw-r--r-- | arch/x86/boot/main.c | 181 |
1 files changed, 181 insertions, 0 deletions
diff --git a/arch/x86/boot/main.c b/arch/x86/boot/main.c new file mode 100644 index 000000000..c421af5a3 --- /dev/null +++ b/arch/x86/boot/main.c @@ -0,0 +1,181 @@ +// 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(); +} |