Re: [Qemu-devel] RFC - best way to organize a multiprotocol transport?

[Anton Ivanov]

On 21/03/14 13:14, Stefan Hajnoczi wrote:
> On Fri, Mar 21, 2014 at 10:01:09AM +0000, Anton Ivanov wrote:
>> I am wondering how to re-organize these so that the code is not
>> duplicated across 3-4 drivers as well as allow people to easily add more
>> encaps in the future.
>> One way will be to pull all common routines into a common file and have
>> different option sets and different inits. Another will be to have
>> "encaps" as a parameter to a common driver. This, however will make all
>> params optional making option parsing ugly and prone to coding errors.
> The user-visible command-line options will be different (e.g. L2TPv3 rx
> cookie).  Therefore, I suggest having independent user-facing netdevs.
>
> In other words, give each encapsulation its own NetdevFooOptions in
> qapi-schema.json and a net_init_foo() function.
>
> qemu -netdev gre,... -netdev l2tp,...

OK.

>
> The actual implementation could be shared.  Maybe something like:
> net/encap.c - common code for encapsulation/tunneling
> net/encap.h - header used by L2TPv3 and GRE
> net/l2tpv3.c - L2TPv3 specific code and net_init_l2tp()
> net/gre.c - GRE specific code and net_init_gre()
>
> How exactly the net/encap.h interface looks is something you need to
> decide based on the details.  Does it make sense to have a common
> NetdevEncap struct that can be embedded and has function pointers for
> protocol-specific hooks?  Or is it better to just provide common
> functions and let protocols use them as a library?  It's up to you.

OK. Undestood.

I will probably collect all common routines and merge them into a
library. Once that is done I will submit a revised patch that does
l2tpv3 and gre.

A

>
> Stefan
>