linux-kernel - Re: [PATCH 40/46] x86/livepatch, lto: Disable live patching with gcc LTO

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Message-ID: <20221114202808.2avu7bscqcyefbpx@two.firstfloor.org>
Date:   Mon, 14 Nov 2022 12:28:09 -0800
From:   Andi Kleen <andi@...stfloor.org>
To:     Josh Poimboeuf <jpoimboe@...nel.org>
Cc:     "Jiri Slaby (SUSE)" <jirislaby@...nel.org>,
        linux-kernel@...r.kernel.org, Andi Kleen <andi@...stfloor.org>,
        Jiri Kosina <jikos@...nel.org>,
        Miroslav Benes <mbenes@...e.cz>,
        Petr Mladek <pmladek@...e.com>,
        Joe Lawrence <joe.lawrence@...hat.com>,
        live-patching@...r.kernel.org, Andi Kleen <ak@...ux.intel.com>,
        Martin Liska <mliska@...e.cz>, Jiri Slaby <jslaby@...e.cz>
Subject: Re: [PATCH 40/46] x86/livepatch, lto: Disable live patching with gcc
 LTO

On Mon, Nov 14, 2022 at 11:07:42AM -0800, Josh Poimboeuf wrote:
> On Mon, Nov 14, 2022 at 12:43:38PM +0100, Jiri Slaby (SUSE) wrote:
> > From: Andi Kleen <andi@...stfloor.org>
> > 
> > It is not supported by gcc 12 so far, so it causes compiler "sorry"
> > messages.
> 
> What specifically is not supported by GCC 12? 

-fwhole-program and the live patching options are mutually exclusive.
Okay I suppose it could be handled by disabling -fwhole-program, although 
that might limit some optimizations.

> What are the "sorry" messages?

It's an error message from the compiler telling you that something is
not implemented.


-Andi