Re: [RFC net-next 1/2] net: dsa: add Realtek RTL8366S switch tag

[Heiner Kallweit <hkallweit1@gmail.com>]

On 17.02.2021 12:01, Linus Walleij wrote:
> On Wed, Feb 17, 2021 at 8:08 AM Heiner Kallweit <hkallweit1@gmail.com> wrote:
> 
>>> +#define RTL8366S_HDR_LEN     4
>>> +#define RTL8366S_ETHERTYPE   0x8899
>>
>> I found this protocol referenced as Realtek Remote Control Protocol (RRCP)
>> and it seems to be used by few Realtek chips. Not sure whether this
>> protocol is officially registered. If yes, then it should be added to
>> the list of ethernet protocol id's in include/uapi/linux/if_ether.h.
>> If not, then it may be better to define it using the usual naming
>> scheme as ETH_P_RRCP in realtek-smi-core.h.
> 
> It's actually quite annoying, Realtek use type 0x8899 for all their
> custom stuff, including RRCP and internal DSA tagging inside
> switches, which are two completely different use cases.
> 
> When I expose raw DSA frames to wireshark it identifies it
> as "Realtek RRCP" and then naturally cannot decode the
> frames since this is not RRCP but another protocol identified
> by the same ethertype.
> 
> Inside DSA it works as we explicitly asks tells the kernel using the
> tagging code in net/dsa/tag_rtl4_a.c that this is the DSA version
> of ethertype 0x8899 and it then goes to dissect the actual
> 4 bytes tag.
> 
> There are at least four protocols out there using ethertype 0x8899.
> 

Ugly .. Thanks for the details!

> Yours,
> Linus Walleij
>