Re: [Openvpn-users] WinCE/PPC; worthwhile to suport? possible?

[James Yonan <jim@xxxxxxxxx>]

Dave wrote:
> I'm going to try and port the client to Pocket PC for my own purposes and am
> wondering:
>
> *  is there any general interest in supporting that platform, and probably
> more importantly,
> *  is this known to be impossible for some reason.  I'm a little surprised
> it hasn't been done already.
>   
I've actually taken a look at the feasibility of this -- my initial 
impression was that it would be difficult simply because a fair amount 
of functionality in the network stack is removed from Windows Mobile/CE 
to satisfy the limited memory of these devices.  For example, Windows 
Mobile/CE doesn't support asynchronous I/O system calls, which OpenVPN 
needs.  I also didn't notice very much support for non-OEM device 
drivers to be added after the OS image has been built by the manufacturer.

The problem (in my view) with Windows Mobile/CE is that it's not really 
Windows -- i.e. you can't simple recompile your code and it "just 
works", because they've made subtle changes/deletions to the Win32 API 
that will break porting.  That sort of defeats the purpose of operating 
systems in the first place -- i.e. providing a standard API to software, 
so that the same software package can run on arbitrary hardware.

Linux doesn't seem to have this problem with preserving the underlying 
system call API even as the OS is downscaled to the embedded space.  You 
can rebuild OpenVPN (or indeed nearly any Linux daemon) without changes 
on a Linksys box running OpenWRT and it just works.

On the other hand, with Windows Mobile/CE, they changed the way device 
drivers work (Drivers on CE are .DLL files, more like libraries than 
conventional device drivers), services don't work the same way, all the 
network utilities are missing (like route, ipconfig, etc.), and they've 
stripped out a key part of the Win32 network stack (i.e. all the 
asynchronous I/O calls).  There isn't even a command prompt shell!

There's also some question about the future viability of the platform -- 
search for "pocket pc is dead" on google groups.

James


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