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Date: Tue, 6 Jul 2021 13:22:01 +0300
From: Leon Romanovsky <leon@kernel.org>
To: Linus Walleij <linus.walleij@linaro.org>
Cc: "a. Miguel Ojeda" <miguel.ojeda.sandonis@gmail.com>,
	ksummit@lists.linux.dev
Subject: Re: [TECH TOPIC] Rust for Linux
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On Tue, Jul 06, 2021 at 11:55:47AM +0200, Linus Walleij wrote:
> On Tue, Jul 6, 2021 at 6:30 AM Leon Romanovsky <leon@kernel.org> wrote:
> 
> > 1. The addition of another language to the mix will hurt a lot our
> > ability to refactor code for cross-subsystem changes.
> >
> > Just as an example, there are many changes in DMA/SG areas that are
> > applicable for many drivers. Even simple grep->replace pattern will
> > be harder and longer if it is needed for the drivers that are written
> > in different languages.
> 
> This is a fair point.
> 
> > 2. Testing matrix will be duplicated, both in compilation tests and in
> > verification coverage. Even now, there are some kernel subsystems that
> > so much in-love with CONFIG_* options that their combination is slightly
> > tested or not tested at all. So imagine, we will need to recompile
> > everything with Rust too and execute same coverage tests again.
> 
> AFAIU the idea is to replace an entire piece of code in C with the
> same piece in Rust, it's not like we are going to develop a second
> kernel in Rust inside the kernel in C. So both/and not either/or.
> I.e. you have to compile some pieces of the kernel written in
> Rust to even get to a working kernel.

Yeah, it can work.

Thanks

> 
> Yours,
> Linus Walleij