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From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Fri, 29 Dec 2017 15:56:32 -0800
Message-ID: <CA+55aFxWWvqDQa-tkvQS7K22t6pYLrk4Q2xkcwoVmnYLsakj5g@mail.gmail.com>
Subject: Re: 4.14.9 with CONFIG_MCORE2 fails to boot
To: Alexander Tsoy <alexander@tsoy.me>,
        =?UTF-8?Q?Toralf_F=C3=B6rster?= <toralf.foerster@gmx.de>
Cc: Dave Hansen <dave.hansen@intel.com>, Greg KH <greg@kroah.com>,
        Andy Lutomirski <luto@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@kernel.org>,
        Borislav Petkov <bp@suse.de>,
        Boris Ostrovsky <boris.ostrovsky@oracle.com>,
        Borislav Petkov <bp@alien8.de>, Borislav Petkov <bpetkov@suse.de>,
        Brian Gerst <brgerst@gmail.com>,
        Dave Hansen <dave.hansen@linux.intel.com>,
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        Denys Vlasenko <dvlasenk@redhat.com>,
        Eduardo Valentin <eduval@amazon.com>,
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        Peter Zijlstra <peterz@infradead.org>, Rik van Riel <riel@redhat.com>,
        Will Deacon <will.deacon@arm.com>,
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        Daniel Gruss <daniel.gruss@iaik.tugraz.at>,
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On Fri, Dec 29, 2017 at 3:15 PM, Alexander Tsoy <alexander@tsoy.me> wrote:
> В Пт, 29/12/2017 в 14:09 -0800, Linus Torvalds пишет:
>>
>> What happens if you take a failing kernel, and then in
>> arch/x86/kernel/traps.c do_double_fault(), you change the
>>
>>   #ifdef CONFIG_X86_ESPFIX64
>>
>> to just a
>>
>>   #if 0
>>
>> do you then get an actual double-fault oops report instead of the
>> stall (and NMI oops)?
>
> This is what I get after disabling ESPFIX64 (see attachment).

Ok, looks like it made no difference for you or for Toralf.

So that was a waste of time. Damn. Also very strange how there's that
double fault in the call trace, but no actual output from any double
fault. Without the ESPFIX64 code, I don't see how that happens, but
since I have no idea what is going on here, I'm obviously missing a
lot.

Hopefully somebody else has a clue or sees something I'm missing.

                      Linus