Re: 4.17.x won't boot due to "x86/boot/compressed/64: Handle 5-level paging boot if kernel is above 4G"

[Andi Kleen]

> At least we need to make user aware about risk of setting custom flags.

There are valid use cases to override the flags. I use it sometimes too,
and know some other people do to.

But you need to know what you're doing. 

Perhaps a warning during build would be reasonable. So if you ask
for a build log you would see it.

-Andi