RE: [pok] The paravirtuailization in POK for RTEMS.

[Herve.Peignelin@xxxxxxxxxxxxxxxxxxx]

Hello,

I have followed your link, and in the
code given in this page, there is an obvious bug in do_IRQ_guest() function.
In effect, your inner loop (on "j"
index) seems to be useless, since you don't use "j" in your code.
After a second check, I think that you
used "i" where you intended to use "j" in your code,
so for exemple:
        if(v->arch.irqdesc[i]..vector
== vector)
should be written
        if(v->arch.irqdesc[j]..vector
== vector)
instead. (Two others indexes follows)

Theoretically, this bug should have
no side effect while you have 16 partitions or less, other than the interrupt
virtualization has little chance to work. From 17 partitions and more,
you have an array overflow, since you're indexing irqdesc[] with the partition
number (i) instead of its intended range (j).
So, I don't think it explains your crash
problem, but I hope this will help you in your debug.

--
Best regards,
Hervé Peignelin.




De :      
 Youren Shen <shenyouren@xxxxxxxxx>
A :      
 pok@xxxxxxxxxxxxxxxxxxx,
Philipp Eppelt <philipp.eppelt@xxxxxxxxxxxxxxxxxxxxx>, Gedare Bloom
<gedare@xxxxxxxxx>
Date :      
 17/08/2014 16:32
Objet :    
   [pok] The paravirtuailization
in POK for RTEMS.

---

Hi, everyone:

I''m a student for Google Summer of Code. this year. My
project, as I described before, is adapt the POK as an hypervisor to run
the RTEMS.
Now I have make some changes in POK kernel,  make
a pull request in github. And I have write a explanation in this wiki page[1]. 

But I'd like to give an brief introduction.
When an interrupt occurs, like time interrupt, we will
mask it in vCPU. when a partition resumes it will check the vCPU, if there
is an interrupt pending on vCPU, then store the interrupt frame and change
eip in the stack of current interrupt as interrupt handler in user spcae.
After interrupt handler, it will invoke an hypercall(syscall) do_iret.
this will check whether there are still some interrupt pending on vCPU.
If no, then restore the interrupt frame and return to normal program execution.

Unlucky, this mechanism is not working now. I have spent
lots of time to debug it.

The pok will crash when I disable all breakpoint and continue it. But if I running step by step, the kernel won't crash. Also the iret can't be tracked(to execute iret once will not cause the crash of POK). I can't locate the reason of this problem, can you give me some suggestions?

Thank you very much.

[1]. http://www.rtems.org/wiki/index.php/GSOC_2014_-_Paravirtualization_of_RTEMS
--
Best Regards.
Youren Shen.