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kernel/linux-rt-4.4.41/arch/um/include/asm/fixmap.h 1.59 KB
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  #ifndef __UM_FIXMAP_H
  #define __UM_FIXMAP_H
  
  #include <asm/processor.h>
  #include <asm/kmap_types.h>
  #include <asm/archparam.h>
  #include <asm/page.h>
  #include <linux/threads.h>
  
  /*
   * 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 {
  	__end_of_fixed_addresses
  };
  
  extern void __set_fixmap (enum fixed_addresses idx,
  			  unsigned long phys, pgprot_t flags);
  
  /*
   * 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_TOP	(TASK_SIZE - 2 * PAGE_SIZE)
  #define FIXADDR_SIZE	(__end_of_fixed_addresses << PAGE_SHIFT)
  #define FIXADDR_START	(FIXADDR_TOP - FIXADDR_SIZE)
  
  #include <asm-generic/fixmap.h>
  
  #endif