I've set up an OS X 10.6 VM that I'm currently testing under Mac OS X 10.6.8, in Parallels 9. I allocated 2.5GB of my MBP's 8GB to the guest, but yet it reports having 4GB. Only Activity Monitor somehow sees the correct amount. This discrepancy has already caused me kpanics due to RAM depletion in a kernel extension. Is this a known issue, something that can happen e.g. because of some configuration file overriding the real memory size?