Message-ID: <20240215075932.66fef954@meshulam.tesarici.cz>
Date: Thu, 15 Feb 2024 07:59:32 +0100
From: Petr Tesařík <petr@...arici.cz>
To: Xin Li <xin@...or.com>
Cc: Dave Hansen <dave.hansen@...el.com>, Petr Tesarik
 <petrtesarik@...weicloud.com>, Jonathan Corbet <corbet@....net>, Thomas
 Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, Borislav
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 "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@...nel.org>, "H.
 Peter Anvin" <hpa@...or.com>, Andy Lutomirski <luto@...nel.org>, Oleg
 Nesterov <oleg@...hat.com>, Peter Zijlstra <peterz@...radead.org>, Xin Li
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 <linux-doc@...r.kernel.org>, open list <linux-kernel@...r.kernel.org>,
 Roberto Sassu <roberto.sassu@...weicloud.com>, Petr Tesarik
 <petr.tesarik1@...wei-partners.com>
Subject: Re: [PATCH v1 0/8] x86_64 SandBox Mode arch hooks

On Wed, 14 Feb 2024 10:52:47 -0800
Xin Li <xin@...or.com> wrote:

> On 2/14/2024 10:22 AM, Petr Tesařík wrote:
> > On Wed, 14 Feb 2024 06:52:53 -0800
> > Dave Hansen <dave.hansen@...el.com> wrote:
> >   
> >> On 2/14/24 03:35, Petr Tesarik wrote:  
> >>> This patch series implements x86_64 arch hooks for the generic SandBox
> >>> Mode infrastructure.  
> >>
> >> I think I'm missing a bit of context here.  What does one _do_ with
> >> SandBox Mode?  Why is it useful?  
> > 
> > I see, I split the patch series into the base infrastructure and the
> > x86_64 implementation, but I forgot to merge the two recipient lists.
> > :-(
> > 
> > Anyway, in the long term I would like to work on gradual decomposition
> > of the kernel into a core part and many self-contained components.
> > Sandbox mode is a useful tool to enforce isolation.
> > 
> > In its current form, sandbox mode is too limited for that, but I'm
> > trying to find some balance between "publish early" and reaching a
> > feature level where some concrete examples can be shown. I'd rather
> > fail fast than maintain hundreds of patches in an out-of-tree branch
> > before submitting (and failing anyway).
> > 
> > Petr T
> >   
> 
> What you're proposing sounds a gigantic thing, which could potentially
> impact all subsystems.

True. Luckily, sandbox mode allows me to move gradually, one component
at a time.

>  Unless you prove it has big advantages with real
> world usages, I guess nobody even wants to look into the patches.
> 
> BTW, this seems another attempt to get the idea of micro-kernel into
> Linux.

We know it's not feasible to convert Linux to a micro-kernel. AFAICS
that would require some kind of big switch, affecting all subsystems at
once.

But with a growing code base and more or less constant bug-per-LOC rate,
people will continue to come up with some ideas how to limit the
potential impact of each bug. Logically, one of the concepts that come
to mind is decomposition.

If my attempt helps to clarify how such decomposition should be done to
be acceptable, it is worthwile. If nothing else, I can summarize the
situation and ask Jonathan if he would kindly accept it as a LWN
article...

Petr T

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