svn commit: r283931 - stable/10/sys/arm/arm

[Warner Losh]

Author: imp
Date: Tue Jun  2 21:36:45 2015
New Revision: 283931
URL: https://svnweb.freebsd.org/changeset/base/283931

Log:
  MFC:
  
  r283014: Disable unmapped I/O: it is broken for unaligned pages
  r283126: Fix comments

Modified:
  stable/10/sys/arm/arm/pmap.c
Directory Properties:
  stable/10/   (props changed)

Modified: stable/10/sys/arm/arm/pmap.c
==============================================================================
--- stable/10/sys/arm/arm/pmap.c	Tue Jun  2 21:24:47 2015	(r283930)
+++ stable/10/sys/arm/arm/pmap.c	Tue Jun  2 21:36:45 2015	(r283931)
@@ -4324,7 +4324,13 @@ pmap_copy_page(vm_page_t src, vm_page_t 
 	pmap_copy_page_func(VM_PAGE_TO_PHYS(src), VM_PAGE_TO_PHYS(dst));
 }
 
-int unmapped_buf_allowed = 1;
+/*
+ * We have code to do unmapped I/O. However, it isn't quite right and
+ * causes un-page-aligned I/O to devices to fail (most notably newfs
+ * or fsck). We give up a little performance to not allow unmapped I/O
+ * to gain stability.
+ */
+int unmapped_buf_allowed = 0;
 
 void
 pmap_copy_pages(vm_page_t ma[], vm_offset_t a_offset, vm_page_t mb[],