cciss: detect bad alignment of scsi commands at build time
cciss: detect bad alignment of scsi commands at build time
Incidentally fix some nearby c++ style comments.
Signed-off-by: Stephen M. Cameron <scameron@beardog.cce.hp.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/drivers/block/cciss_cmd.h b/drivers/block/cciss_cmd.h
index 515c9f0..e624ff9 100644
--- a/drivers/block/cciss_cmd.h
+++ b/drivers/block/cciss_cmd.h
@@ -167,10 +167,13 @@
#define CMD_MSG_TIMEOUT 0x05
#define CMD_MSG_STALE 0xff
-/* This structure needs to be divisible by 8 for new
- * indexing method. PAD_32 and PAD_64 can be adjusted
- * independently as needed for 32-bit and 64-bits systems.
+/* This structure needs to be divisible by COMMANDLIST_ALIGNMENT
+ * because low bits of the address are used to to indicate that
+ * whether the tag contains an index or an address. PAD_32 and
+ * PAD_64 can be adjusted independently as needed for 32-bit
+ * and 64-bits systems.
*/
+#define COMMANDLIST_ALIGNMENT (8)
#define IS_64_BIT ((sizeof(long) - 4)/4)
#define IS_32_BIT (!IS_64_BIT)
#define PAD_32 (0)