Author: emaste
Date: Fri Mar 2 00:21:07 2012
New Revision: 232372
URL: http://svn.freebsd.org/changeset/base/232372
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@.
Sponsored by: Sandvine Incorporated
Modified:
stable/9/sys/x86/x86/busdma_machdep.c
Directory Properties:
stable/9/sys/ (props changed)
Modified: stable/9/sys/x86/x86/busdma_machdep.c
==============================================================================
--- stable/9/sys/x86/x86/busdma_machdep.c Fri Mar 2 00:15:52 2012
(r232371)
+++ stable/9/sys/x86/x86/busdma_machdep.c Fri Mar 2 00:21:07 2012
(r232372)
@@ -227,6 +227,14 @@ bus_dma_tag_create(bus_dma_tag_t parent,
bus_dma_tag_t newtag;
int error = 0;
+ /* Always enforce at least a 4GB (2GB for PAE) boundary. */
+#if defined(__amd64__)
+ if (boundary == 0 || boundary > ((bus_addr_t)1 << 32))
+ boundary = (bus_size_t)1 << 32;
+#elif defined(PAE)
+ 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;
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