Hi Norman, 

Thank you for the examples, does it make difference if i  don't pass my input-output POD struct by reference  since it need to be copied to the server side, and later from the server to the client. 
from the point view of  performance  which one is the best if we add the option of placing my POD in shared memory. 

best, 

> Subject: Re: RPC parameters
> To: genode-main@...98....net
> From: norman.feske@...1...
> Date: Thu, 14 Jan 2016 11:26:56 +0100
>
> Hello,
>
> > Genode is new to me . I just start playing with it.
>
> welcome to the list!
>
> > I was looking at the Hello program and the RPC mechanism. as i
> > understood RPC does not support passing pointer as parameter
> > how i can pass a parameter by reference where i need to change its value
> > in the server side.
>
> you can find a detailed description of the RPC mechanism in Section
> 8.12. "Remote procedure calls" of the manual [1]. In short, you have two
> options:
>
> 1. Define a POD struct used as return type of your RPC functiion.
> For an example, take a look that the Framebuffer::Session::mode
> RPC function [2].
>
> 2. You can pass a reference to a POD object as RPC argument.
> This is rarely used but you can find find an example in the
> Raspberry-Pi-specific platform-session interface, namely the
> setup_framebuffer RPC function [3].
>
> [1] http://genode.org/documentation/genode-foundations-15-05.pdf
> [2]
> https://github.com/genodelabs/genode/blob/master/repos/os/include/framebuffer_session/framebuffer_session.h#L91
> [3]
> https://github.com/genodelabs/genode/blob/master/repos/os/include/spec/rpi/platform_session/platform_session.h#L39
>
> Cheers
> Norman
>
> --
> Dr.-Ing. Norman Feske
> Genode Labs
>
> http://www.genode-labs.com · http://genode.org
>
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