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Date:   Tue, 11 Oct 2022 10:04:43 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Sami Tolvanen <samitolvanen@google.com>
Cc:     Miguel Ojeda <ojeda@kernel.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-fsdevel@vger.kernel.org, patches@lists.linux.dev,
        Jarkko Sakkinen <jarkko@kernel.org>,
        Kees Cook <keescook@chromium.org>,
        Alex Gaynor <alex.gaynor@gmail.com>,
        Wedson Almeida Filho <wedsonaf@google.com>,
        David Gow <davidgow@google.com>,
        Boqun Feng <boqun.feng@gmail.com>, Gary Guo <gary@garyguo.net>,
        =?iso-8859-1?Q?Bj=F6rn?= Roy Baron <bjorn3_gh@protonmail.com>,
        Jonathan Corbet <corbet@lwn.net>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        Dave Hansen <dave.hansen@linux.intel.com>, x86@kernel.org,
        "H. Peter Anvin" <hpa@zytor.com>, linux-doc@vger.kernel.org
Subject: Re: [PATCH v10 25/27] x86: enable initial Rust support
Message-ID: <Y0Ujm6a6bV3+FWM3@hirez.programming.kicks-ass.net>
References: <20220927131518.30000-1-ojeda@kernel.org>
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On Mon, Oct 10, 2022 at 04:15:33PM -0700, Sami Tolvanen wrote:
> On Fri, Oct 7, 2022 at 10:18 AM Peter Zijlstra <peterz@infradead.org> wrote:
> >
> > On Tue, Sep 27, 2022 at 03:14:56PM +0200, Miguel Ojeda wrote:
> > > Note that only x86_64 is covered and not all features nor mitigations
> > > are handled, but it is enough as a starting point and showcases
> > > the basics needed to add Rust support for a new architecture.
> >
> > Does it fail the build if required options are missing? Specifically are
> > things like kCFI and IBT enabled? Silently not handling those will
> > result in an unbootable image.
> 
> Rust supports IBT with -Z cf-protection=branch, but I don't see this
> option being enabled in the kernel yet. Cross-language CFI is going to
> require a lot more work though because the type systems are not quite
> compatible:

Right; so where does that leave us? Are we going to force disable rust
when kCFI is selected ?