Min RAM and ROM footprints

[Norman Feske]

Hi Daniel,

On 01/29/2014 08:08 AM, Daniel Waddington wrote:
> Can someone give me a guestimate (or better) on the minimum RAM and ROM
> footprints for ARM (lets say PBXA9) for genode-hw and genode+foc, to run
> a minimal printf program? 

I just did a small experiment (see the attached patch). To determine how
much RAM is needed to run the test-printf on hw_pbxa9, I successively
shrunk the physical RAM visible to base-hw. Of the two RAM regions of
the PBX-A9 platform, I kept only RAM0, starting at 0x70000000. This is
the address where the boot image is loaded to.

Apparently, setting RAM0_SIZE to 0x240000 (ca. 2.3 MiB) is enough to run
core + init + test-printf on PBX-A9 via base-hw.

I think that a further reduction is possible but it will take a bit more
work. Also, compiling the system with -Os would eventually help to get
the value smaller.

> Also, I wonder if there are other open source microkernels aimed at tiny
> memory footprints - can you suggest any?

Sorry, I'm afraid that I cannot recommend a suitable kernel from the tip
of my head. However, once I stumbled over the following project at
GitHub, which looks pretty interesting (I have not tried it through):

  https://github.com/f9micro/f9-kernel

Cheers
Norman

-- 
Dr.-Ing. Norman Feske
Genode Labs

http://www.genode-labs.com · http://genode.org

Genode Labs GmbH · Amtsgericht Dresden · HRB 28424 · Sitz Dresden
Geschäftsführer: Dr.-Ing. Norman Feske, Christian Helmuth
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