From mboxrd@z Thu Jan  1 00:00:00 1970
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Date: Sat, 17 Feb 2007 18:44:43 +0100
From: Jan Kiszka <jan.kiszka@domain.hid>
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Subject: [Xenomai-core] Re: Magics of [CAN] message filtering
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To: Oliver Hartkopp <socketcan@domain.hid>
Cc: socketcan-core@domain.hid, xenomai-core <xenomai@xenomai.org>

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Oliver Hartkopp wrote:
> When you're touching anything inside your API, have you ever thought to=
 add
>=20
> __attribute__ ((aligned(8)))
>=20
> to the data[8] element of the struct can_frame?
>=20
> This would enable you to make 64 bit compares directly in the data
> section of the can_frame ...
>=20
> typedef __u32 canid_t;
>=20
> struct can_frame {
>     canid_t can_id;  /* 32 bit CAN_ID + EFF/RTR/ERR flags */
>     __u8    can_dlc; /* data length code: 0 .. 8 */
>     __u8    data[8] __attribute__ ((aligned(8)));
> };

[Swallowing down my well-known opinion on typeof(can_dlc) :)]

Yes, this should be done, already for the more urging sake of
unambiguous layout of the structure across the kernel/user space border.

Jan


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