On 06/01/2021 Daniel Pocock wrote:
Most packages compiled on one type of kernel will run on the other type
but there could be a very small number that have to be recompiled if the
Fedora kernel changes down to 4k.
I'm afraid changing the page size would be more complicated than that.
The same way that some projects assume everyone has a 4K page size, there are projects
that assume ppc64le has a 64K page size .
One could argue that both types of projects have to change their code and be independent
of the page size and I'd agree with that. But there are projects whose storage format
depend on the page size, e.g. PMDK.
Other projects may assume ppc64le has a 64K page size in order to improve performance,
For this particular case, the current code works well on 4K page size, without any
downgrade in performance. If modified to use 4K page size, it would have a negative impact
on users with 64K page size.
Regardless of the packages above, I still think the Btrfs issue is
biggest surprise for people and it is worse because it is the default
filesystem now. People can reboot into a new kernel but they may not be
able to easily reformat their disks after mkfs at 64k.
Likewise for PMDK. I wouldn't be surprised if it works without any code changes, but I
don't think anyone has tested it.