Comment # 2 on bug 1136803 from Christian Boltz

(In reply to Marcus H�we from comment #1)
> I'm not sure if there is a "sane default". It probably depends on the package
> you are building.

Agreed, but I'm also quite sure that we can agree that "OOM directly after
booting the kernel" does not qualify as "sane default" ;-)

If you want a good answer, you'll probably have to check the build statistics
of various packages. My selfish answer is that apparmor needs about 500 MB
(interestingly more in the devel project, no idea why), so 512 MB are just
enough.

Given today's RAM size, I'd say 512 MB (or maybe even 1 GB - hey, sometimes
your browser {needs,eats} more ;-) is a sane default.