Limitations/gotchas of kexec?

[Clif Houck]

Hi all,

I was wondering if there's a known list of limitations of kexec?

For example, is there anything fundamentally wrong with trying to kexec
from kernel version X to kernel version Y where:
1) version Y > version X
2) X < Y
3) X == Y

I wouldn't expect to have an issue in case 1 or 3. But maybe if the
distance between two kernel versions is too great then I would have a
problem? Is there any concept of explicit incompatibility between
different kernels coupled with kexec or is it just 'try-and-see'?

Are there other important things to look out for?

Thanks,
Clif Houck