arch/i386-pc/exec/cachecleare.c

   1 /*
   2     Copyright © 1995-2015, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc: CacheClearE() - Clear the caches with extended control.
   6     Lang: english
   7 */
   8
   9 #include <exec/types.h>
  10 #include <exec/execbase.h>
  11 #include <aros/libcall.h>
  12
  13 void Exec_Wbinvd();
  14
  15 #include <proto/exec.h>
  16
  17 AROS_LH3(void, CacheClearE,
  18     AROS_LHA(APTR, address, A0),
  19     AROS_LHA(ULONG, length, D0),
  20     AROS_LHA(ULONG, caches, D1),
  21     struct ExecBase *, SysBase, 107, Exec)
  22 /*
  23     INTERNALS
  24         Although this function is not needed for BM-DMA on x86 due to
  25         strong cache coherency (the CPU snoops the address lines and
  26         invalidates all out-of-date cache), it is needed for some other
  27         operations. For example, when updating graphics memory address
  28         translation tables, changes may be invisible to the graphics
  29         card/chip if not explicitly written back from the cache.
  30
  31         Drivers performing DMA operations should use
  32         CachePreDMA()/CachePostDMA() instead, which maximise performance
  33         on x86 by doing nothing!
  34 */
  35 {
  36     AROS_LIBFUNC_INIT
  37
  38     /* A full flush has been requested */
  39     if (length == 0xFFFFFFFF)
  40     {
  41         Supervisor((ULONG_FUNC)Exec_Wbinvd);
  42         return;
  43     }
  44
  45     /* A partial flush requested */
  46     if (caches & CACRF_ClearD)
  47     {
  48         /* TODO: Detect if CPU supports clflush instruction and use it instead
  49            of wbinvd to provide more optimized cache flushes */
  50         Supervisor((ULONG_FUNC)Exec_Wbinvd);
  51     }
  52
  53     AROS_LIBFUNC_EXIT
  54 } /* CacheClearE */
  55