linux-kernel - Re: [RFC Patch 0/7] kernel: Introduce multikernel architecture support

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Message-ID: <aM-aDAIbKqBMN2DQ@kernel.org>
Date: Sun, 21 Sep 2025 09:24:12 +0300
From: Mike Rapoport <rppt@...nel.org>
To: Jan Engelhardt <ej@...i.de>
Cc: Cong Wang <xiyou.wangcong@...il.com>, linux-kernel@...r.kernel.org,
	pasha.tatashin@...een.com, Cong Wang <cwang@...tikernel.io>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Baoquan He <bhe@...hat.com>, Alexander Graf <graf@...zon.com>,
	Changyuan Lyu <changyuanl@...gle.com>, kexec@...ts.infradead.org,
	linux-mm@...ck.org
Subject: Re: [RFC Patch 0/7] kernel: Introduce multikernel architecture
 support

On Sun, Sep 21, 2025 at 07:54:31AM +0200, Jan Engelhardt wrote:
> 
> On Friday 2025-09-19 00:25, Cong Wang wrote:
> 
> >This patch series introduces multikernel architecture support, enabling
> >multiple independent kernel instances to coexist and communicate on a
> >single physical machine.
> >
> >Each kernel instance can run on dedicated CPU
> >cores while sharing the underlying hardware resources.
> 
> I initially read it in such a way that that kernels run without
> supervisor, and thus necessarily cooperatively, on a system.
> 
> But then I looked at
> <https://multikernel.io/assets/images/comparison-architecture-diagrams.svg>,

The diagram also oversimplifies containers, with system containers the "OS"
runs inside the container and only the kernel is shared.

It's interesting to hear how the multikernel approach compare to system
containers as well.

> saw that there is a kernel on top of a kernel, to which my reactive
> thought was: "well, that has been done before", e.g. User Mode Linux.
> While UML does not technically talk to hardware directly, continuing
> the thought "what's stopping a willing developer from giving /dev/mem
> to the subordinate kernel".
> 
> On second thought, a hypervisor is just some kind of "miniature
> kernel" too (if generalizing very hard).
> 

-- 
Sincerely yours,
Mike.