Re: in kernel 2.6.x, tun/tap nic supports vlan packets

[zhuyj <zyjzyj2000@gmail.com>]

Hi, Jaso

Would you like to code review these 2 patches?

Thanks a lot.
Zhu Yanjun
On 04/17/2014 11:35 AM, zhuyj wrote:
> Hi, all
>
> In kernel 2.6.x, linux depends on nic vlan hardware acceleration to 
> insert/extract
> vlan tag. In this scene, in kernel 2.6.x
>
>                  _____        ________
>     A           |     | B    |        | C
>  vlan packets-->| tap |----->|vlan nic|--->
>                 |_____|      |________|
>
> We hope vlan packets pass through tap and vlan nic from A to c.
> But in kernel 2.6.x, linux kernel can not extract vlan tag. It depends
> on nic vlan hardware acceleration. It is well known that tap nic has no
> vlan acceleration. So in the above scene, vlan packets can not be 
> handled by
> tap nic. These vlan packets will be discarded in B. They can not 
> arrive at C.
>
> In kernel 3.x, linux can handle vlan packets. It does not depend on 
> nic vlan
> hardware acceleration. So the above scene can work well in kernel 3.x.
>
> To resolve the above in kernel 2.6.x, we simulated vlan hardware 
> acceleration in
> tun/tap driver. Then followed the logic of commit commit 4fba4ca4
> [vlan: Centralize handling of hardware acceleration] to modify the 
> vlan packets
> process in kernel 2.6.x. In the end, the above scene can work well in 
> patched
> kernel 2.6.x.
>
> Please comment on it. Any reply is appreciated.
>
> Hi, Willy
>
> These 2 patches are for linux2.6.x. These can work well here. Please 
> help to merge
> linux 2.6.32.x. Thanks a lot.
>
> Best Regards!
> Zhu Yanjun
>