How to boot CoreOS with different ramdisk size

Question

I am trying to boot CoreOS from a PXE server using ramdisk. However, no matter what size of ramdisk I specify (with ramdisk_size) CoreoOS always takes half of the memory as a ramdisk. Can anyone tell me how to specify the ramdisk size at boot?

Answer 1

This has to do with the default nature of temporary filesystems in that they will default to 50% as the limit but won't reserve that much memory; actual usage will grow over time, but will not exceed the 50% limit.

Also you'll find this in the official CoreOS docs regarding PXE:

The filesystem will consume more RAM as it grows, up to a max of 50%. The limit isn't currently configurable.