From: David Miller <davem@davemloft.net>
Sent: Thursday, April 8, 2021 4:46 PM
...

quoted

+struct gdma_msg_hdr {
+	u32 hdr_type;
+	u32 msg_type;
+	u16 msg_version;
+	u16 hwc_msg_id;
+	u32 msg_size;
+} __packed;
+
+struct gdma_dev_id {
+	union {
+		struct {
+			u16 type;
+			u16 instance;
+		};
+
+		u32 as_uint32;
+	};
+} __packed;

Please don't  use __packed unless absolutely necessary.  It generates
suboptimal code (byte at a time
accesses etc.) and for many of these you don't even need it.

In the driver code, all the structs/unions marked by __packed are used to
talk with the hardware, so I think __packed is necessary here?

Do you think if it's better if we remove all the __packed, and add
static_assert(sizeof(struct XXX) == YYY) instead? e.g.

@@ -105,7 +105,8 @@ struct gdma_msg_hdr {
        u16 msg_version;
        u16 hwc_msg_id;
        u32 msg_size;
-} __packed;
+};
+static_assert(sizeof(struct gdma_msg_hdr) == 16);

 struct gdma_dev_id {
        union {

Now I'm trying to figure out how other NIC drivers define structs/unions.

Thanks,
Dexuan