Re: [RFC 0/5] parker: PARtitioned KERnel

[Dave Hansen]

On 9/23/25 08:31, Fam Zheng wrote:
> In terms of fault isolation or security, all kernel instances share
> the same domain, as there is no supervising mechanism. A kernel bug
> in any partition can cause problems for the whole physical machine.
> This is a tradeoff for low-overhead / low-complexity, but hope in
> the future we can take advantage of some hardware mechanism to
> introduce some isolation.
I just don't think this is approach is viable. The buck needs to stop
_somewhere_. You can't just have a bunch of different kernels, with
nothing in charge of the system as a whole.

Just think of bus locks. They affect the whole system. What if one
kernel turns off split lock detection? Or has a different rate limit
than the others? What if one kernel is a big fan of WBINVD? How about
when they use resctrl to partition an L3 cache? How about microcode updates?

I'd just guess that there are a few hundred problems like that. Maybe more.

I'm not saying this won't be useful for a handful of folks in a tightly
controlled environment. But I just don't think it has a place in
mainline where it needs to work for everyone.