Re: [Adeos-main] FW: [PATCH] repost: ARM FCSE

[Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>]

Gilles Chanteperdrix wrote:
> Gilles Chanteperdrix wrote:
>> Richard Cochran wrote:
>>> I posted this patch today on linux-arm-kernel, but I repeat it
>>> here because there does not seem to be too much interest on that
>>> list for the ARM FCSE.
>>>
>>> I also tried to combine this patch with ipipe for kernel 2.6.20
>>> running on the Intel IXDP465, but after booting I soon get a BUG.
>>>
>>> Anyhow, perhaps the ARM people might take a look at combining
>>> ipipe with FCSE...
>> Ok. Six monthes later, I finally gave a try to your patch on at91rm9200,
>> which supports FCSE as well.
>>
>> When booting, I get random segmentation faults (either with or without
>> the I-pipe), assertion which fails in glibc, and such things.
> 
> A small update: I get the same random failures with a vanilla kernel
> (without I-pipe patch at all).
> 
> I will now investigate pmd_populate.

Hi Richard,

I changed a few bits here and there in your patch, but I believe the
biggest problem was that Linux seem to recycle pids faster than it
recycles mm_struct, so we ended up with processes sharing the same
space, and since the pid allocation mechanism was a bit too naive for
multi-threaded applications, I changed it to a bitfield based solution.
I now have an FCSE kernel which seems much more stable (and without the
double mapping either). This is the good news.

The bad news is that I still get mysterious crashes. So, will now
investigate.

Regards.

-- 
					    Gilles.