On 15.02.24 11:43, Guy Harris wrote:
On Feb 15, 2024, at 12:01 AM, Oliver Hartkopp <socketcan@xxxxxxxxxxxx> wrote:
https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git/commit/?id=c83c22ec1493c0b7cc77327bedbd387e295872b6
How does one request that the VCID information be provided on a PF_PACKET socket (whether SOCK_RAW or SOCK_DGRAM)?
The VCID is now part of the content in the struct skbuff data. So it is
available everywhere, where a formerly CAN ID was accessible. Also on
PACKET sockets.
The VCID is no VLAN tag, nor uses it the VLAN specific skbuff elements
in Linux.
While it would have been possible to get a VLAN tag via PACKET sockets
auxiliary cmsg mechanic you would never have be able to "write" the VCID
in this way as user space application - and especially not as
unprivileged user. And this is a vital requirement for logging and
replaying CAN (CC/FD/XL) traffic.
The question if we could invent some VLAN-like CAN interface (can0.123)
is to be discussed. But there would be the need of a use-case of real
CAN XL users. So far there is nothing to see.
As CAN XL has up to 2048 bytes of payload it is also possible to do
IP-over-CANXL. IMHO it would make sense to create a software ethernet
device (maybe with VLAN tag) that interacts with a CAN XL network
interface. But this is future work, again when there will be a use-case.
Best regards,
Oliver
