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RIOT/boards/x86-multiboot-common/startup.c 4.43 KB
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  /*
   * Copyright (C) 2014  René Kijewski  <rene.kijewski@fu-berlin.de>
   *
   * This library is free software; you can redistribute it and/or
   * modify it under the terms of the GNU Lesser General Public
   * License as published by the Free Software Foundation; either
   * version 2.1 of the License, or (at your option) any later version.
   *
   * This library is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * Lesser General Public License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with this library; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
   */
  
  /**
   * @ingroup     boards_x86-multiboot
   * @{
   *
   * @file
   * @brief       Startup code to be loaded by multiboot enabled bootloaders.
   *
   * @author      René Kijewski <rene.kijewski@fu-berlin.de>
   *
   * @}
   */
  
  #include <cpu.h>
  #include <multiboot.h>
  #include <x86_kernel_memory.h>
  #include <x86_memory.h>
  #include <x86_reboot.h>
  #include <x86_videoram.h>
  
  #include <inttypes.h>
  #include <stdint.h>
  #include <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  
  #ifndef BREAK_STARTUP
  #   define BREAK_STARTUP (0)
  #endif
  
  static void __attribute__((noreturn)) startup(uint32_t multiboot_magic, const multiboot_info_t *multiboot_info);
  void __attribute__((noreturn, optimize("Os", "omit-frame-pointer"), no_instrument_function)) _start(void);
  
  extern const multiboot_header_t multiboot_header __attribute__((section("._multiboot_header")));
  const multiboot_header_t multiboot_header = {
      .magic = MULTIBOOT_HEADER_MAGIC,
      .flags = MULTIBOOT_HEADER_FLAGS,
      .checksum = (-(MULTIBOOT_HEADER_MAGIC + MULTIBOOT_HEADER_FLAGS)),
      .header_addr = (uintptr_t) &multiboot_header,
      .load_addr = (uintptr_t) &_kernel_memory_start,
      .load_end_addr = (uintptr_t) &_section_data_end,
      .bss_end_addr = (uintptr_t) &_section_bss_end,
      .entry_addr = (uintptr_t) &_start,
  };
  
  void __attribute__((noreturn, optimize("Os", "omit-frame-pointer"), no_instrument_function)) _start(void)
  {
      __asm__ volatile ("xor %ebp, %ebp");
      __asm__ volatile ("push %ebp");
      __asm__ volatile ("push %ebx");
      __asm__ volatile ("push %eax");
      __asm__ volatile ("push %ebp");
      __asm__ volatile ("jmp *%0" :: "r"(&startup));
      __builtin_unreachable();
  }
  
  static const multiboot_info_t *multiboot_info;
  
  bool x86_get_memory_region(uint64_t *start, uint64_t *len, unsigned long *pos)
  {
      while (1) {
          if (*pos >= multiboot_info->mmap_length) {
              return false;
          }
  
          const multiboot_memory_map_t *mmap = (void *)(multiboot_info->mmap_addr + *pos);
          *pos += mmap->size + 4;
  
          *start = mmap->addr;
          *len = mmap->len;
  
          uint64_t end = *start + *len;
          printf("  %08lx%08lx - %08lx%08lx ", (long) (*start >> 32), (long) *start, (long) (end >> 32), (long) end);
  
          if (mmap->type != 1) {
              // not free (ignore reclaimable RAM)
              const char *msg;
              switch (mmap->type) {
                  case 2: msg = "reseved"; break;
                  case 3: msg = "ACPI [reclaimable]"; break;
                  case 4: msg = "ACPI [NVS]"; break;
                  case 5: msg = "bad memory"; break;
                  default: msg = "unknown";
              }
              printf("(unusable: %s)\r\n", msg);
          }
          else {
              puts("(usable)");
              return true;
          }
      }
  }
  
  static void have_a_break(void)
  {
      volatile bool cnt = false;
      while (!cnt) {
          __asm__ volatile ("pause");
      }
  }
  
  static void __attribute__((noreturn)) startup(uint32_t multiboot_magic, const multiboot_info_t *multiboot_info_)
  {
      x86_init_gdt(); /* load GDT early */
      x86_load_empty_idt(); /* just a safeguard to cause a tripple fault, not really needed */
  
  #if BREAK_STARTUP
      have_a_break();
  #else
      (void) have_a_break;
  #endif
  
      memset(&_section_bss_start, 0, &_section_bss_end - &_section_bss_start + 1);
  
      videoram_puts(" Booting RIOT \r\n");
      if (multiboot_magic != MULTIBOOT_BOOTLOADER_MAGIC) {
          videoram_puts(" Multiboot magic is wrong \r\n");
          x86_hlt();
      }
      else if (!(multiboot_info->flags && MULTIBOOT_INFO_MEM_MAP)) {
          videoram_puts(" Multiboot is lacking memory map information \r\n");
          x86_hlt();
      }
  
      multiboot_info = multiboot_info_;
      x86_startup();
  }