Avnish Chouhan [off-list ref] writes:

Change RMA size from 512 MB to 768 MB which will result 
in more RMA at boot time for PowerPC.

Did you consider just increasing it to 1GB?

It's possible there's some folks running LPARs with less than 1GB, but
they are unlikely to continue doing so by the time this change trickles
into distros. To be supported modern RHEL requires 2GB minimum RAM
anyway.

Can you also describe the behaviour users will see when they configure
an LPAR with less than 768MB of RAM.

cheers