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Subject: Re: linux-5.10.11 build failure
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     LKML <linux-kernel@vger.kernel.org>, stable@vger.kernel.org
References: <f141f12d-a5b9-1e60-2740-388bf350b631@googlemail.com>
 <YBKFNUp5WYtdg9pE@kroah.com>
From:   Chris Clayton <chris2553@googlemail.com>
Message-ID: <fef32b91-89fe-64b8-fe57-d681db29f86e@googlemail.com>
Date:   Thu, 28 Jan 2021 10:05:43 +0000
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On 28/01/2021 09:34, Greg Kroah-Hartman wrote:
> On Thu, Jan 28, 2021 at 09:17:10AM +0000, Chris Clayton wrote:
>> Hi,
>>
>> Building 5.10.11 fails on my (x86-64) laptop thusly:
>>
>> ..
>>
>>  AS      arch/x86/entry/thunk_64.o
>>   CC      arch/x86/entry/vsyscall/vsyscall_64.o
>>   AS      arch/x86/realmode/rm/header.o
>>   CC      arch/x86/mm/pat/set_memory.o
>>   CC      arch/x86/events/amd/core.o
>>   CC      arch/x86/kernel/fpu/init.o
>>   CC      arch/x86/entry/vdso/vma.o
>>   CC      kernel/sched/core.o
>> arch/x86/entry/thunk_64.o: warning: objtool: missing symbol for insn at offset 0x3e
>>
>>   AS      arch/x86/realmode/rm/trampoline_64.o
>> make[2]: *** [scripts/Makefile.build:360: arch/x86/entry/thunk_64.o] Error 255
>> make[2]: *** Deleting file 'arch/x86/entry/thunk_64.o'
>> make[2]: *** Waiting for unfinished jobs....
>>
>> ..
>>
>> Compiler is latest snapshot of gcc-10.
>>
>> Happy to test the fix but please cc me as I'm not subscribed
> 
> Can you do 'git bisect' to track down the offending commit?
> 

Sure, but I'll hold that request for a while. I updated to binutils-2.36 on Monday and I'm pretty sure that is a feature
of this build fail. I've reverted binutils to 2.35.1, and the build succeeds. Updated to 2.36 again and, surprise,
surprise, the kernel build fails again.

I've had a glance at the binutils ML and there are all sorts of issues being reported, but it's beyond my knowledge to
assess if this build error is related to any of them.

I'll stick with binutils-2.35.1 for the time being.

> And what exact gcc version are you using?
>

 It's built from the 10-20210123 snapshot tarball.

I can report this to the binutils folks, but might it be better if the objtool maintainer looks at it first? The
binutils change might just have opened the gate to a bug in objtool.

> thanks,
> 
> greg k-h
> 

Thanks.

Chris