On Tue, 2016-08-23 at 21:09 +0100, Al Viro wrote: > On Tue, Aug 23, 2016 at 11:24:06AM -0700, David Miller wrote: > > > On some versions and architectures. Can you guarantee that you will > > > notice when an exception appears? > > Again, show me the assembler output exhibiting the lack of > > initialization, for this specific structure and situation. > > > > That's all that I'm asking. > ... and then we can file a bug report against the sodding compiler. Note > that > struct ethtool_wolinfo { > __u32 cmd; > __u32 supported; > __u32 wolopts; > __u8 sopass[SOPASS_MAX]; // 6, actually > }; > is not going to *have* padding. Not on anything even remotely sane. > If array of 6 char as member of a struct requires 64bit alignment on some > architecture, I would really like some of what the designers of that ABI > must have been smoking.
try this on x86-64 $ pahole -C ethtool_wolinfo vmlinux struct ethtool_wolinfo { __u32 cmd; /* 0 4 */ __u32 supported; /* 4 4 */ __u32 wolopts; /* 8 4 */ __u8 sopass[6]; /* 12 6 */ /* size: 20, cachelines: 1, members: 4 */ /* padding: 2 */ /* last cacheline: 20 bytes */ };