[LITMUS^RT] Can not register DEMO Scheduler Plugin in LITMUS^RT

[Glenn Elliott]

On Jan 2, 2014, at 10:54 PM, Sanjib Das <cnt.sanjib at googlemail.com> wrote:

> Dear Concern,
> 
> Thank you for your reply. Finally I am able to sort out the problem. It was a problem with my grub configuration. It was not loading the right kernel package. 
> 
> 
> Now I am advancing with the DEMO plug in tutorial.
> I have another question. Do I have to compile the whole kernel package each time I make any change in the demo plug in code.
> I am asking this question cause it takes a huge time to make bzImage and install it each time.
> So any suggestion to reduce the whole plug in implementation will be helpful more than I can say.
> 
> Thanks in advance 
> 
> Sanjib 

I’m afraid that you will have to recompile the kernel.  Although troublesome, recompiling usually doesn’t take very long.  Are you compiling directly in an ARM platform?  If so, you really aught to be using cross-compilation.  If you’re on x86, then it is likely that you have far too many options (specifically, drivers) enabled in your .config.  This can happen if you’re using a .config taken from a Linux distribution.  These are crafted to allow the kernel to run on practically any system with nearly every supported Linux driver.  You really only need to build what is necessary to run on your specific platform.

Even with a stripped down .config, {recompiling, installing, re-booting}* can be annoying when you’re deep in development.  We suggest that you initially test/run your kernel in a Qemu/KVM virtual machine.  This will allow you to test for algorithmic correctness.  A wonderful thing about developing in Qemu is that you can attach gdb and single-step kernel code, follow pointers, and dump/inspect memory buffers.  Once your algorithms look solid, then you move on to testing real-time correctness on a native platform (hopefully your system is stable at this point).  There are several links in the litmus-rt wiki regarding development in a VM (including VM images): https://wiki.litmus-rt.org/litmus/

-Glenn