linux-kernel - Re: [RFC 0/5] parker: PARtitioned KERnel

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Message-ID: <f4041bf7-0984-4aff-887f-f77e58525e3a@zytor.com>
Date: Tue, 23 Sep 2025 12:46:38 -0700
From: "H. Peter Anvin" <hpa@...or.com>
To: Fam Zheng <fam.zheng@...edance.com>, linux-kernel@...r.kernel.org
Cc: Lukasz Luba <lukasz.luba@....com>, linyongting@...edance.com,
        songmuchun@...edance.com, satish.kumar@...edance.com,
        Borislav Petkov <bp@...en8.de>, Thomas Gleixner <tglx@...utronix.de>,
        yuanzhu@...edance.com, Ingo Molnar <mingo@...hat.com>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Zhang Rui <rui.zhang@...el.com>, fam@...hon.net, x86@...nel.org,
        liangma@...edance.com, Dave Hansen <dave.hansen@...ux.intel.com>,
        "Rafael J. Wysocki" <rafael@...nel.org>, guojinhui.liam@...edance.com,
        linux-pm@...r.kernel.org, Thom Hughes <thom.hughes@...edance.com>
Subject: Re: [RFC 0/5] parker: PARtitioned KERnel

On 2025-09-23 08:31, Fam Zheng wrote:
> 
> Parker is a proposed feature in linux for multiple linux kernels to run
> simultaneously on single machine, without traditional kvm virtualisation. This
> is achieved by partitioning the CPU cores, memory and devices for
> partitioning-aware Linux kernel.
> 

This seems to be much better handled by a lightweight hypervisor. There is a
reason why ALL IBM mainframes have a low-level hard-partitioning hypervisor.

Typically that hypervisor will expose a static, very low level view of the
machine (e.g. no scheduling - VCPUs are mapped 1:1 to physical CPUs; no I/O
sharing or emulation, except possibly as needed to boot, and so on.)

Because the functionality of the hypervisor is so limited, the overhead is
minimal, but it CAN (but doesn't HAVE TO) provide memory and I/O isolation
between partitions.

	-hpa