When called to do a transfer that has a start offset within the cache line which is uneven between source and destination and a length which terminates the source of the copy exactly on a cache line, one extra line gets copied into a temporary buffer. This is normally not an issue since the buffer is a kernel buffer and only the requested information gets copied into the user buffer. The problem arises when the source ends at the very last physical page of memory. That last cache line does not exist and results in the SHUB chip raising an MCA. Signed-off-by: Robin Holt <holt@xxxxxxx> Signed-off-by: Dean Nelson <dcn@xxxxxxx> Index: linux-2.6/arch/ia64/sn/kernel/bte.c =================================================================== --- linux-2.6.orig/arch/ia64/sn/kernel/bte.c 2006-09-27 14:06:15.000000000 -0500 +++ linux-2.6/arch/ia64/sn/kernel/bte.c 2006-11-14 20:36:16.779928325 -0600 @@ -381,14 +381,13 @@ bte_result_t bte_unaligned_copy(u64 src, * bcopy to the destination. */ - /* Add the leader from source */ - headBteLen = len + (src & L1_CACHE_MASK); - /* Add the trailing bytes from footer. */ - headBteLen += L1_CACHE_BYTES - (headBteLen & L1_CACHE_MASK); - headBteSource = src & ~L1_CACHE_MASK; headBcopySrcOffset = src & L1_CACHE_MASK; headBcopyDest = dest; headBcopyLen = len; + + headBteSource = src - headBcopySrcOffset; + /* Add the leading and trailing bytes from source */ + headBteLen = L1_CACHE_ALIGN(len + headBcopySrcOffset); } if (headBcopyLen > 0) { - To unsubscribe from this list: send the line "unsubscribe linux-ia64" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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