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Add an XSCALE_CACHE_READ_WRITE_ALLOCATE option for people who

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want to play fast-and-loose.
This commit is contained in:
thorpej 2002-08-09 21:49:09 +00:00
parent 884bc64586
commit 6ce0a206cc
1 changed files with 21 additions and 2 deletions
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23
sys/arch/arm/arm32/pmap.c
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@ -1,4 +1,4 @@
/* $NetBSD: pmap.c,v 1.105 2002/08/09 18:22:59 thorpej Exp $ */
/* $NetBSD: pmap.c,v 1.106 2002/08/09 21:49:09 thorpej Exp $ */
/*
* Copyright (c) 2002 Wasabi Systems, Inc.
@ -143,7 +143,7 @@
#include <machine/param.h>
#include <arm/arm32/katelib.h>
__KERNEL_RCSID(0, "$NetBSD: pmap.c,v 1.105 2002/08/09 18:22:59 thorpej Exp $");
__KERNEL_RCSID(0, "$NetBSD: pmap.c,v 1.106 2002/08/09 21:49:09 thorpej Exp $");
#ifdef PMAP_DEBUG
#define PDEBUG(_lev_,_stat_) \
if (pmap_debug_level >= (_lev_)) \
@ -3848,6 +3848,25 @@ pmap_pte_init_xscale(void)
pte_l2_s_cache_mode = L2_B|L2_C;
pte_l2_s_cache_mask = L2_S_CACHE_MASK_xscale;
#ifdef XSCALE_CACHE_READ_WRITE_ALLOCATE
/*
* The XScale core has an enhanced mode where writes that
* miss the cache cause a cache line to be allocated. This
* is significantly faster than the traditional, write-through
* behavior of this case.
*
* However, there is a bug lurking in this pmap module, or in
* other parts of the VM system, or both, which causes corruption
* of NFS-backed files when this cache mode is used. We have
* an ugly work-around for this problem (disable r/w-allocate
* for managed kernel mappings), but the bug is still evil enough
* to consider this cache mode "experimental".
*/
pte_l1_s_cache_mode |= L1_S_XSCALE_TEX(TEX_XSCALE_X);
pte_l2_l_cache_mode |= L2_XSCALE_L_TEX(TEX_XSCALE_X);
pte_l2_s_cache_mode |= L2_XSCALE_T_TEX(TEX_XSCALE_X);
#endif /* XSCALE_CACHE_READ_WRITE_ALLOCATE */
#ifdef XSCALE_CACHE_WRITE_THROUGH
/*
* Some versions of the XScale core have various bugs in