l4shmnet and its structure

Adam Lackorzynski adam at os.inf.tu-dresden.de
Fri Jun 13 21:57:23 CEST 2014


On Wed Jun 11, 2014 at 00:16:47 +0200, cem akpolat wrote:
> As far as I tested, l4smnet.c file establishes a communication channel
> between client ann server l4linux and I asked couple of weeks ago about the
> posibility of multiple clients and one server example and Adam recommended
> me to use one of the l4linux, in this case server, as a router. That is
> exactly the way that I am following. For this reason, I tried first of all
> a simple example: one server two clients with two different shm.
> Interestingly, I couldn't see the second client. I couldn't evaluate
> whether this trial was logical or not, but if this works for one of the
> clients why not for the second?

So I understand that you configured one L4Linux with two l4shmnet
network interfaces and one of those two did not work? Hard to tell for
me what's wrong without more info.
> Apart from this case, I attempt to convert l4shmnet from two l4linux to
> multiple case, but this is really not easy. I tried one shared memory first
> of all, modifying some parts of the code is quite difficult, you can easily
> encounter a failure such as page_fault. That's why I did two shared memory
> as mentioned above. My simple question, which way is really more logical,
> 1- using one shared memory for all clients and server or 2- multiple shared
> memory for each separate client. Is there any document or source snippet
> that I can to use a similar structure in l4re. shm code is already here,
> but it doesn't really give insight into this part.

I think there's no need to change anything in the Linux driver (except
bugs of course). For each connection (between two Linuxes) there's a
separate shared memory and one Linux can be configured to pass packets
between its interfaces. Now doing it like a switch would require a
separate component where all Linuxes talk it and the component copies
the packets accordingly. 

Adam                 adam at os.inf.tu-dresden.de
  Lackorzynski         http://os.inf.tu-dresden.de/~adam/

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