[uClinux-dev] Questions regarding real-time implications of uClinux

[Michael Schnell]

> if there are good books or resources on the web that would describe 
> techniques for controlling hardware under uClinux 
"Linux Device drivers" is the standard
> that would help compensate for the fact it is not a true real-time OS.  
Linux is not a realtime OS (nor is µCLinux). As you have an FPGA you can 
do the hard realtime stuff in "hardware" or add a second processor in 
the FPGA and run it without an OS for the hard realtime stuff
> The Suzaku provided uClinux kernel is 2.4 if that makes a difference 
> as to what features are or are not available to drivers or 
> applications to help with real-time performance.
I don't know Suzaku. But Kernel 2.6 is said to perform a lot better 
regarding (soft) realtime than 2.4. So you should upgrade.
There are some Linux "realtime patches". Most are integrated in Kernel 
2.6 anyway, but AFAIK there are some that can be applied to the standard 
2.6. But they might be unusable with µCLinux and/or the Microblaze 
processor.
>
> uClinux provides a rich environment of tools and applications to 
> assist with software development that I would strongly prefer to us it 
> than other more minimal environments that have true real-time 
> characteristics.  As with anything, things like this are always a 
> trade-off and I hope that I'm making the right decision.
After a really long research process I, too, decided to use an FPGA with 
a processor running µCLinux for my projects. (I decided to use 
Altera/NIOS, as I seem to get better processor features in comparably 
prised FPGAs here.) One decision criteria was the ability to implement 
virtual peripherals (_really_ hard realtime stuff). This can perfectly 
be done using VHDL programming.

-Michael