On 12.02.2024 16:26:34, Oliver Hartkopp wrote: > I'm currently in discussion with Guy Harris who's working on the Linux-CAN > support in Wireshark. > > We current have two approaches how to integrate the VCID into the struct > canxl_frame: > > 1. Add the VCID at a specific 16 bit offset (above the 11 bit Prio ID) > 2. Create a endian-dependent data structure with a separate uint8 VCID > > 1: https://lore.kernel.org/linux-can/20240212151404.60828-1-socketcan@xxxxxxxxxxxx/ > 2: https://lore.kernel.org/linux-can/20240128183758.68401-1-socketcan@xxxxxxxxxxxx/ > > The endian-dependent data structure looks like this: > > struct canxl_frame { > #if defined(__LITTLE_ENDIAN) > __u16 prio; /* 11 bit priority for arbitration */ > __u8 vcid; /* virtual CAN network identifier */ > __u8 __res0; /* reserved / padding must be set to zero */ > #elif defined(__BIG_ENDIAN) > __u8 __res0; /* reserved / padding must be set to zero */ > __u8 vcid; /* virtual CAN network identifier */ > __u16 prio; /* 11 bit priority for arbitration */ > #else > #error "Unknown endianness" > #endif > __u8 flags; /* additional flags for CAN XL */ > __u8 sdt; /* SDU (service data unit) type */ > __u16 len; /* frame payload length in byte */ > __u32 af; /* acceptance field */ > __u8 data[CANXL_MAX_DLEN]; > }; > > @Guy: Besides the fact that suggestion 2 does not win a design prize I'm not > sure whether solution 1 or 2 are better to maintain over lifetime. > > Feedback about the two suggestions is highly appreciated. Then I'll skip the virtual CAN network identifier support patches for now. Marc -- Pengutronix e.K. | Marc Kleine-Budde | Embedded Linux | https://www.pengutronix.de | Vertretung Nürnberg | Phone: +49-5121-206917-129 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-9 |
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