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