svn commit: r232354 - in stable/8/sys: amd64/amd64 i386/conf i386/i386

[Ed Maste]

Author: emaste
Date: Thu Mar  1 19:43:28 2012
New Revision: 232354
URL: http://svn.freebsd.org/changeset/base/232354

Log:
  MFC r232267:
    Workaround for PCIe 4GB boundary issue
  
    Enforce a boundary of no more than 4GB - transfers crossing a 4GB
    boundary can lead to data corruption due to PCIe limitations.  This
    change is a less-intrusive workaround that can be quickly merged back
    to older branches; a cleaner implementation will arrive in HEAD later
    but may require KPI changes.
  
    This change is based on a suggestion by jhb at .
  
  Approved by:	re
  Reviewed by:	jhb (MFC)
  Reviewed by:	jhb, scottl (original)
  Sponsored by:	Sandvine Incorporated

Modified:
  stable/8/sys/amd64/amd64/busdma_machdep.c
  stable/8/sys/i386/i386/busdma_machdep.c
Directory Properties:
  stable/8/sys/   (props changed)
  stable/8/sys/amd64/include/xen/   (props changed)
  stable/8/sys/boot/   (props changed)
  stable/8/sys/cddl/contrib/opensolaris/   (props changed)
  stable/8/sys/contrib/dev/acpica/   (props changed)
  stable/8/sys/contrib/pf/   (props changed)
  stable/8/sys/dev/e1000/   (props changed)
  stable/8/sys/i386/conf/XENHVM   (props changed)

Modified: stable/8/sys/amd64/amd64/busdma_machdep.c
==============================================================================
--- stable/8/sys/amd64/amd64/busdma_machdep.c	Thu Mar  1 19:17:56 2012	(r232353)
+++ stable/8/sys/amd64/amd64/busdma_machdep.c	Thu Mar  1 19:43:28 2012	(r232354)
@@ -216,6 +216,10 @@ bus_dma_tag_create(bus_dma_tag_t parent,
 	bus_dma_tag_t newtag;
 	int error = 0;
 
+	/* Always enforce at least a 4GB boundary. */
+	if (boundary == 0 || boundary > ((bus_addr_t)1 << 32))
+		boundary = (bus_size_t)1 << 32;
+
 	/* Basic sanity checking */
 	if (boundary != 0 && boundary < maxsegsz)
 		maxsegsz = boundary;

Modified: stable/8/sys/i386/i386/busdma_machdep.c
==============================================================================
--- stable/8/sys/i386/i386/busdma_machdep.c	Thu Mar  1 19:17:56 2012	(r232353)
+++ stable/8/sys/i386/i386/busdma_machdep.c	Thu Mar  1 19:43:28 2012	(r232354)
@@ -226,6 +226,12 @@ bus_dma_tag_create(bus_dma_tag_t parent,
 	bus_dma_tag_t newtag;
 	int error = 0;
 
+#if defined(PAE)
+	/* Need at least a 4GB boundary, PAE limitations require 2GB */
+	if (boundary == 0 || boundary > ((bus_addr_t)1 << 31))
+		boundary = (bus_size_t)1 << 31;
+#endif
+
 	/* Basic sanity checking */
 	if (boundary != 0 && boundary < maxsegsz)
 		maxsegsz = boundary;