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Message-ID: <2024061842-hatless-viewpoint-5024@gregkh>
Date: Tue, 18 Jun 2024 18:44:16 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: Sami Tolvanen <samitolvanen@...gle.com>
Cc: Masahiro Yamada <masahiroy@...nel.org>,
Luis Chamberlain <mcgrof@...nel.org>,
Miguel Ojeda <ojeda@...nel.org>,
Matthew Maurer <mmaurer@...gle.com>,
Alex Gaynor <alex.gaynor@...il.com>,
Wedson Almeida Filho <wedsonaf@...il.com>,
Gary Guo <gary@...yguo.net>, linux-kbuild@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-modules@...r.kernel.org,
rust-for-linux@...r.kernel.org
Subject: Re: [PATCH 00/15] Implement MODVERSIONS for Rust
On Mon, Jun 17, 2024 at 05:58:19PM +0000, Sami Tolvanen wrote:
> Hi folks,
>
> This series implements CONFIG_MODVERSIONS for Rust, an important
> feature for distributions like Android that want to ship Rust
> kernel modules, and depend on modversions to help ensure module ABI
> compatibility.
>
> There have been earlier proposals [1][2] that would allow Rust
> modules to coexist with modversions, but none that actually implement
> symbol versioning. Unlike C, Rust source code doesn't have sufficient
> information about the final ABI, as the compiler has considerable
> freedom in adjusting structure layout for improved performance [3],
> for example, which makes using a source code parser like genksyms
> a non-starter. Based on Matt's suggestion and previous feedback
> from maintainers, this series uses DWARF debugging information for
> computing versions. DWARF is an established and relatively stable
> format, which includes all the necessary ABI details, and adding a
> CONFIG_DEBUG_INFO dependency for Rust symbol versioning seems like a
> reasonable trade-off.
>
> The first 12 patches of this series add a small tool for computing
> symbol versions from DWARF, called gendwarfksyms. When passed a list
> of exported symbols, the tool generates an expanded type string
> for each symbol, and computes symbol CRCs similarly to genksyms.
> gendwarfksyms is written in C and uses libdw to process DWARF, mainly
> because of the existing support for C host tools that use elfutils
> (e.g., objtool).
That's cool, can the C code be switched to also use this? That way we
only have one path/code for all of this?
thanks,
greg k-h
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