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RIOT/cpu/x86/include/x86_kernel_memory.h 3.13 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
   */
  
  /**
   * Layout of the kernel memory. The symbols are set in the linker.ld.
   *
   * @ingroup x86
   * @{
   * @file
   * @author  René Kijewski <rene.kijewski@fu-berlin.de>
   */
  
  #ifndef KERNEL_MEMORY_H__
  #define KERNEL_MEMORY_H__
  
  #ifdef __cplusplus
  extern "C" {
  #endif
  
  /**
   * @brief   First byte inside the elf segments.
   *
   * Expected to be the start of the high memory, i.e. 1MB.
   */
  extern char _kernel_memory_start;
  
  /**
   * @brief   Start of first byte of code inside the .text segment.
   *
   * This symbol does not have to be aligned.
   */
  extern char _section_text_start;
  
  /**
   * @brief   First byte after the code.
   *
   * This symbol does not have to be aligned.
   */
  extern char _section_text_end;
  
  /**
   * @brief   First byte inside the .rodata segment.
   *
   * This symbol is expected to be aligned.
   */
  extern char _section_rodata_start;
  
  /**
   * @brief   First byte after the .rodata segment.
   *
   * This symbol does not have to be aligned.
   */
  extern char _section_rodata_end;
  
  /**
   * @brief   First byte inside the .data segment.
   *
   * This symbol is expected to be aligned.
   */
  extern char _section_data_start;
  
  /**
   * @brief   First byte after the .data segment.
   *
   * This symbol does not have to be aligned, since it shares the same previleges as the .bss segment.
   */
  extern char _section_data_end;
  
  /**
   * @brief   Start of the .bss segment.
   *
   * Probably unaligned.
   * The .bss segment must follow the .data segment with no other segment inbetween.
   * It's likely that `&_section_data_end == &_section_bss_start`.
   */
  extern char _section_bss_start;
  
  /**
   * @brief   First byte after the .bss segment.
   *
   * This symbol should not to be aligned, because RAM cycles would be wasted to clear unused bytes otherwise.
   */
  extern char _section_bss_end;
  
  /**
   * @brief   First byte after the last of the common elf segments.
   *
   * This symbol is expected to be aligned.
   * The "common elf segments" are .text, .rodata, .data and .bss.
   * All the (physical) memory beyond this point will be overwritten at the pleasure of the kernel.
   */
  extern char _kernel_memory_end;
  
  /**
   * @brief   First byte that may be mapped as the heap
   *
   * This symbol is expected to be aligned.
   * Must be bigger than _kernel_memory_end.
   * There should be a space between _kernel_memory_end and _heap_start, but it does not have to.
   */
  extern char _heap_start;
  
  #ifdef __cplusplus
  }
  #endif
  
  #endif
  
  /** @} */