Increase L4linux ramdisk size ?

Julien Heyman bidsomail at gmail.com
Thu Apr 7 18:33:29 CEST 2011


Hi Adam,

Thanks for the RAM_SIZE_MB tip, I now have 512 Mb properly detected/usable
on my BB xM.
The test scenario still fails as before though (if I keep the RAM/ramdisk
settings I mentionned previously). I will increase the amount of RAM I
allocate to each L4linux instance, to workaround the problem, but in case
you find something interesting on the reason for this behavior I am of
course still interested to know.

Regards,
Julien

On Thu, Apr 7, 2011 at 3:42 PM, Adam Lackorzynski <adam at os.inf.tu-dresden.de
> wrote:

> Hi Julien,
>
> On Wed Apr 06, 2011 at 16:42:07 +0200, Julien Heyman wrote:
> > Here is what I notice now: it seems to be related to memory settings
> > somehow. Even though my ramdisk is indeed smaller than half the ram size
> I
> > assign to the linux instance loading it, the presence of other L4Re
> > executables (that take their share of the global memory...) has an
> impact,
> > as illustrated in the tests below:
> >
> > Test 1:
> > - I am running two instances of L4Linux simultaneously. The first
> instance
> > gets 16Mb RAM and has a ramdisk of ~3Mb, while the second instance gets
> 40Mb
> > RAM and has a ramdisk of 16Mb => in this case the boot fails in the
> second
> > linux instance, with the symptoms I mentionned earlier, when loading the
> > 16Mb ramdisk (full log attached)
> >
> > Test 2:
> > - same setup, but I comment out the creation of the first linux instance
> in
> > the boot script => in this case the 16Mb ramdisk is properly loaded in
> the
> > "second" linux and boot is OK (full log attached)
> >
> > Test 3:
> > - similar setup as test 1, running two linux instances, but this time
> > reducing the ramdisk in the second instance to 8Mb instead of 16Mb: boot
> is
> > OK in this case too (full log attached)
>
> I'll try to reproduce this. It didn't work in the first try but I'll try
> harder.
>
> > Do the logs and/or my test descriptions above allow to understand the
> reason
> > for the failed case ?
> > As a side question, I see at boot time that Fiasco uses a total of only
> 128
> > Mb of RAM, whereas the Beagleboard xM I am using has 512 Mb RAM. Is this
> > amount predefined somewhere in Fiasco, or does it autodetect available
> RAM
> > at boot time ? (and in this case why doesn't it see the full 512 Mb ?)
>
> The reason is simple. The older Beagleboard (without 'xM') has 128MB, so
> this is the default setting. When building the image, add
> RAM_SIZE_MB=512 to the make command and it will use 512MB. Adding it to
> conf/Makeconf.boot will make it the default.
>
>
> Adam
> --
> Adam                 adam at os.inf.tu-dresden.de
>  Lackorzynski         http://os.inf.tu-dresden.de/~adam/
>
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