Re: [PATCH 00/15] Implement MODVERSIONS for Rust

Sami Tolvanen
2024-07-18T17:04:41Z

On Tue, Jul 16, 2024 at 12:12 AM Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> > After replacement:
> >
> > union {
> > u64 new_member;
> > struct {
> > u8 __kabi_reserved_1[8];
> > };
> > }
>
> Note, such a thing would only be for the distros that want it, you can
> add support for this to the tool, but there is no need for any
> __kabi_reserved fields in mainline.

Sure. I assume modversions are primarily useful for distros, so I just
want to make sure this scheme can handle all the common issues as
well.

> > Greg, I know you've been dealing with this for a long time, any thoughts?
>
> It's a good start, yes. Also watch out for when structures go from
> "anonymous" to "fully described" when new #include lines get added to
> files. The current tooling has issues with that, so we need to use
> __GENKSYMS__ #ifdef lines in some places to keep crc generation stable.
> Don't know if dwarf output would be susceptible to the same issues with
> that or not, but you should check.

That's a great point. DWARF output has the exact same problem if a
structure declaration later becomes a definition, but I think we can
come up with a solution for this issue too in v2.

Sami