[dpdk-dev] [PATCH v2 14/16] fm10k/base: TLV structures must be 4byte aligned, not 1byte aligned

Wang Xiao W xiao.w.wang at intel.com
Wed Jan 27 04:50:45 CET 2016

Per comments from an upstream patch, and looking at how TLV LE_STRUCT
code works, we actually want these structures to be 4byte aligned, not
1byte aligned. In practice, 1byte alignment has worked so far because
all our structures end up being a multiple of 4. But if a future TLV
structure were added that had a u8 or similar sticking on the end things
would break. Fix this by using 4byte alignment which will prevent the
TLV LE_STRUCT code from breaking. Update the comment explaining that we
need 4byte alignment of our structures.

Signed-off-by: Wang Xiao W <xiao.w.wang at intel.com>
 drivers/net/fm10k/base/fm10k_pf.h | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/net/fm10k/base/fm10k_pf.h b/drivers/net/fm10k/base/fm10k_pf.h
index 92e2962..ee8527a 100644
--- a/drivers/net/fm10k/base/fm10k_pf.h
+++ b/drivers/net/fm10k/base/fm10k_pf.h
@@ -91,14 +91,14 @@ enum fm10k_pf_tlv_attr_id_v1 {
-/* The following data structures are overlayed specifically to TLV mailbox
- * messages, and must not have gaps between their values. They must line up
- * correctly to the TLV definition.
+/* The following data structures are overlayed directly onto TLV mailbox
+ * messages, and must not break 4 byte alignment. Ensure the structures line
+ * up correctly as per their TLV definition.
 #ifdef C99
-#pragma pack(push, 1)
+#pragma pack(push, 4)
-#pragma pack(1)
+#pragma pack(4)
 #endif /* C99 */
 struct fm10k_mac_update {

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