l4lx_memory_map_virtual_page messages ending in internal error

[Uwe Geuder]

Hi!

On Fri Jul 11, 2014 at 19:52:29 +0300, Uwe Geuder wrote:
> As mentioned in a previous thread I tried xz compression of my
> initramfs image in L4Linux on ARM. When L4Linux tried to decompress the
> following messages occured:
> 
> > Trying to unpack rootfs image as initramfs...
> > l4lx_memory_map_virtual_page: Already used, existing is 2400020
> > l4lx_memory_map_virtual_page: cannot attach vpage (2ca64000, 2816324f): -99
> > l4lx_memory_map_virtual_page: Already used, existing is 2400020
> 
> and the same messages (with increasing address) repeated for a zillion
> of times until it eventually ended like this:

On Mon, 14 Jul 2014 23:46:11 +0200, Adam Lackorzynski wrote:
> How much memory did you give L4Linux and how big is the initrd
> (compressed and uncompressed)?

The device has 1 GB of RAM. L4Linux is configured with mem=650M.  The
initramfs is about 260 MB uncompressed, around 70 MB xz compressed.

Originally I tried with xz options not ideal for the puprpose, so
uncompression of the image would have required 65 MB of memory. Still
that's only 10% of the memory assgined to L4Linux, I am quite sure
there is plenty of free memory around. Well, with 2 reservations.

- The data about how much memory is needed for uncompression is
reported by xz -l on the host, the kernel uses XZ embedded. Still I
would find it suprising if the xz embedded implementation required
more memory than the full size implementation.

- And I don't know from which pool the kernel allocates memory
when uncompressing initramfs. Could that be a pool with much lower
limit than the full 650 MB?

I still repeated the exercise twice. First with the xz options given
in the kernel source. Unompression of that image is reported to take
33 MB of memory. Then I tried once more with even mored restrictive
options, so that the image can be uncomressed with 17 MB of memory.
The error messages were the same in all cases. I had the feeling that
for the image requiring less memory for uncompression the
l4lx_memory_map_virtual_page error was repeated less often than for
the originak image. However, I did not count. (I could still do that,
if it is valuable information.)

Regards,

Uwe Geuder
Nomovok Ltd.
Tampere, Finland
uwe.gxuder at nomovok.com (bot test: humans correct 1 obvious spelling error)