[linux-dvb] Re: Linux on SAT receivers

[Felix Domke <tmbinc@elitedvb.net>]

Stramaglia, Carlo wrote:

> Dear Holger,
>
> thanks for your info. 
> I find very interesting the statement "For all other boxes you can simply
> build your own kernel".
>
> Are you saying that Linux can boot on every STB by just recompiling the
> Kernel?
>  
basically, there are a few things to consider:

- The available memory.
This might the criterium where most boxes faill. Althought some 
uclinux-variants run with 4MB of ram, it gets useful starting with 16MB. 
For example, the dbox2 has 32MB RAM (+2MB for Framebuffer and demux)
- The used CPU-core.
Unless you have years of time, you have to use a cpu-architecture  where 
linux is already ported for, for example MIPS, PowerPC or x86.
As the STI55xx-Series have a ST20-based CPU, you would even have to 
implement support in the gnu-toolchain AND port the kernel to a 
completely new architecture. This is REALLY HARD work, compared to 
"just" porting to a specific cpu. For example, for the dbox2, where the 
MPC823 (66MHz embedded PowerPC) is used, there was already support in 
the kernel.
- the not-out-of-the-box-supported stuff.
Even if you choose a STB where Linux would "run" by "just compiling a 
kernel" (and making small board-specific patches), you would have to 
write drivers for the DVB-chipset. Most probably there aren't any 
documents about this, and no drivers available. This was for example the 
hardest task in the dbox2-project (after being able to run code on the box).
- useful interfaces
If you run linux, you like to have a network port, otherwise it doesn't 
make too much sense. Firewire or USB might do it, too, but complicate 
the whole thing.

After all, i haven't seen any other mass-market STB other than the 
d-Box2 where enough hardware resources were available to run a decent 
linux (except of course the DM7000, but this box was designed for linux).


I'm, for myself, very interested in the upcoming, commercial Linux-based 
Boxes (for comparisation), but unfortunally i haven't seen any of them.

felix




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