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

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Message-ID: <0a0a3922-dc42-0c42-ecac-b63641ee07d6@suse.cz>
Date:   Tue, 15 Nov 2022 14:32:28 +0100
From:   Martin Liška <mliska@...e.cz>
To:     Josh Poimboeuf <jpoimboe@...nel.org>,
        Andi Kleen <andi@...stfloor.org>
Cc:     "Jiri Slaby (SUSE)" <jirislaby@...nel.org>,
        linux-kernel@...r.kernel.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>,
        Jiri Slaby <jslaby@...e.cz>
Subject: Re: [PATCH 40/46] x86/livepatch, lto: Disable live patching with gcc
 LTO

On 11/14/22 23:00, Josh Poimboeuf wrote:
> On Mon, Nov 14, 2022 at 12:28:09PM -0800, Andi Kleen wrote:
>> 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.
> 
> What live patching options are you referring to?
> 

As mentioned in the reply to the next email, we speak about:
https://gcc.gnu.org/onlinedocs/gcc/Optimize-Options.html#index-flive-patching
option:

gcc -flto -flive-patching=inline-clone a.c
cc1: sorry, unimplemented: live patching is not supported with LTO

Cheers,
Martin