correct length of bcm message

[Patrick Menschel <menschel.p@xxxxxxxxx>]

Hi,

is anyone writing to BCMSocket on the Raspberry Pi from Python3 ?

I'm digging through an endianess / alignment issue on armhf platform.

My testcode [1] that I wrote years ago on works on X86_64 platform but
fails on armhf platform with OSERROR 22 "invalid argument".

Then I started concatenating bytes by hand instead of using ctypes.

What I came around is that frames[0] is somehow expected to be 8 bytes
length although it should be 16 bytes.

struct bcm_msg_head {
...
        struct can_frame frames[0];
};

I ended up inserting padding 8 bytes instead of frames[0] value and that
actually works.

That makes my overall BCMHead 40 bytes and the complete bcm message
including the can frame 56bytes.

[1] https://github.com/menschel/pysocketcan

Thanks,
Patrick