Timing problem on mem_fpage_unmap() in the fiasco kernel

[Ryan C. Spring]

Just curious, when your senior had DROPS working on OMAP, was it just
the ARM core of the chip or did you also port/write something for using
the DSP core of the processor?

Regards,
Ryan Spring


WanKeun Jo wrote:
>
> Hi,
>
> I've been working on porting DROPS to Bulverde board - PXA270. My
> senior already made
>
> DROPS work on OMAP board before. He worked with L4Linux-2.6.16, but I
> don't know
>
> exact version of fiasco kernel and L4Env packages because they are not
> specified.
>
>
> I got all the sources from my senior - not the latest things.. - and
> have tried them work on Bulverde board.
>
>
> My status is that I have an unsolvable error in fiasco kernel.
>
>
>
> On L4Linux-2.6.16's booting process, one step is "Freeing INITRD", and
> system halted on that point.
>
> By tracing codes, I got to know while the mem_fpage_unmap() function in
> l4/kernel/fiasco/src/kern/map_util.cpp executed, the system halted.
>
> And I put "delay codes" into that function's for() {}, and then the
> system continued to execute and
>
> boot succeed. I found this fact after I added printf() into that code
> in order to debug.
>
>
>
> On that point - "Freeing INITRD", whether the boot process goes next
> step or not
>
> depends on how much delay time is put on that code, mem_fpage_unmap().
> If I make the delay time
>
> a little bit longer, then the system goes to next step at that point,
> but stops somewhere else after that.
>
> If I make the delay time too short, the system never go to next step.
>
>
> And the mem_fpage_unmap() is called a lot while the system works, but
> only in the "Freeing INITRD"
>
> part, the problem appears.
>
>
>
> I think this is a serious timing error, but I can't know what the
> problem is. I already tried all the
>
> combinations of kernel and L4Linux options before.
>
>
> when I tried to install the latest kernel and l4linux-2.6.18, the
> halting problem
>
> didn't appear. And I found that the latest kernel's mem_fpage_unmap()
> functions implementation has
>
> a lot of changes compared to the kernel I work with.
>
>
>
>
> Could you help me solve this problem??
>
> Please don't say to me "use the latest one".. My senior already
> succeed on OMAP board with the
>
> old versions.
>
>
> Thank you.
> ------------------------------------------------------------------------
>
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-- 
************************************************************************
Ryan C. Spring 

Doctoral Student
Computer Science Department
Computer Science Building, Room 320
University of Texas at El Paso (UTEP)
El Paso, TX 79968 
USA

+1 915 539 7311 (cell)

http://www.spring-west.net/ryan
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