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-rw-r--r--arch/x86/boot/main.c185
1 files changed, 185 insertions, 0 deletions
diff --git a/arch/x86/boot/main.c b/arch/x86/boot/main.c
new file mode 100644
index 000000000..c4ea5258a
--- /dev/null
+++ b/arch/x86/boot/main.c
@@ -0,0 +1,185 @@
+// 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)));
+
+struct port_io_ops pio_ops;
+
+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)
+{
+ init_default_io_ops();
+
+ /* 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();
+}