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kernel/linux-rt-4.4.41/arch/mips/include/asm/fixmap.h 2.29 KB
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  /*
   * fixmap.h: compile-time virtual memory allocation
   *
   * This file is subject to the terms and conditions of the GNU General Public
   * License.  See the file "COPYING" in the main directory of this archive
   * for more details.
   *
   * Copyright (C) 1998 Ingo Molnar
   *
   * Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999
   */
  
  #ifndef _ASM_FIXMAP_H
  #define _ASM_FIXMAP_H
  
  #include <asm/page.h>
  #include <spaces.h>
  #ifdef CONFIG_HIGHMEM
  #include <linux/threads.h>
  #include <asm/kmap_types.h>
  #endif
  
  /*
   * Here we define all the compile-time 'special' virtual
   * addresses. The point is to have a constant address at
   * compile time, but to set the physical address only
   * in the boot process. We allocate these special  addresses
   * from the end of virtual memory (0xfffff000) backwards.
   * Also this lets us do fail-safe vmalloc(), we
   * can guarantee that these special addresses and
   * vmalloc()-ed addresses never overlap.
   *
   * these 'compile-time allocated' memory buffers are
   * fixed-size 4k pages. (or larger if used with an increment
   * highger than 1) use fixmap_set(idx,phys) to associate
   * physical memory with fixmap indices.
   *
   * TLB entries of such buffers will not be flushed across
   * task switches.
   */
  
  /*
   * on UP currently we will have no trace of the fixmap mechanizm,
   * no page table allocations, etc. This might change in the
   * future, say framebuffers for the console driver(s) could be
   * fix-mapped?
   */
  enum fixed_addresses {
  #define FIX_N_COLOURS 8
  	FIX_CMAP_BEGIN,
  	FIX_CMAP_END = FIX_CMAP_BEGIN + (FIX_N_COLOURS * 2),
  #ifdef CONFIG_HIGHMEM
  	/* reserved pte's for temporary kernel mappings */
  	FIX_KMAP_BEGIN = FIX_CMAP_END + 1,
  	FIX_KMAP_END = FIX_KMAP_BEGIN+(KM_TYPE_NR*NR_CPUS)-1,
  #endif
  	__end_of_fixed_addresses
  };
  
  /*
   * used by vmalloc.c.
   *
   * Leave one empty page between vmalloc'ed areas and
   * the start of the fixmap, and leave one page empty
   * at the top of mem..
   */
  #define FIXADDR_SIZE	(__end_of_fixed_addresses << PAGE_SHIFT)
  #define FIXADDR_START	(FIXADDR_TOP - FIXADDR_SIZE)
  
  #include <asm-generic/fixmap.h>
  
  #define kmap_get_fixmap_pte(vaddr)					\
  	pte_offset_kernel(pmd_offset(pud_offset(pgd_offset_k(vaddr), (vaddr)), (vaddr)), (vaddr))
  
  /*
   * Called from pgtable_init()
   */
  extern void fixrange_init(unsigned long start, unsigned long end,
  	pgd_t *pgd_base);
  
  
  #endif