From: Ursula Braun <ubraun@xxxxxxxxxxxxx> Date: Mon, 12 Nov 2018 17:01:32 +0100 > +/* SMC-D cursor format */ > +union smcd_cdc_cursor { ... > +} __aligned(8); > struct smcd_cdc_msg { ... > + union smcd_cdc_cursor prod; > + union smcd_cdc_cursor cons; > u8 res3[8]; > } __packed; You're asking for 8-byte alignment of an object you only embed in a __packed structure, which therefore has arbitary alignment. It's not going to work.