What is the minimum amount of RAM required to run Linux kernel on an Embedded device?

Question

What is the minimum amount of RAM required to run Linux kernel on an Embedded device? In Linux-0.11 for 80x86, the minimum RAM required was 2MB to load the kernel data structures and interrupt vectors.

How much is the minimum needed RAM for present Linux-3.18 kernel? Does different architectures like x86 and ARM have different requirements for minimum RAM required for booting? How does one calculates the same?

Answer 1

This site suggests:

A minimal uClinux configuration could be run from 4MB RAM, although the recommendation we are giving to our customers is that they should design in at least 16 MB's worth of RAM.

If you are using SDRAM, the problem would be getting a part any smaller than 16Mb at reasonable volume cost and availability, so maybe it is a non-problem? For SRAM however, that is a large and relatively expensive part.

eLinux.org has a lot of information on embedded kernel size, how to determine it, and how to minimise it.