linux-kernel - Re: [PATCHv2 0/4] x86: 5-level related changes into decompression code

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Message-ID: <C6812C12-2ABB-486B-99F8-14FD99ABFB98@zytor.com>
Date:   Wed, 29 Nov 2017 13:03:46 -0800
From:   hpa@...or.com
To:     Andi Kleen <ak@...ux.intel.com>,
        "Kirill A. Shutemov" <kirill@...temov.name>
CC:     Thomas Gleixner <tglx@...utronix.de>, Borislav Petkov <bp@...e.de>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Ingo Molnar <mingo@...hat.com>, x86@...nel.org,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Andy Lutomirski <luto@...capital.net>,
        Cyrill Gorcunov <gorcunov@...nvz.org>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCHv2 0/4] x86: 5-level related changes into decompression code

On November 29, 2017 12:58:15 PM PST, Andi Kleen <ak@...ux.intel.com> wrote:
>> We're really early in the boot -- startup_64 in decompression code --
>and
>> I don't know a way print a message there. Is there a way?
>> 
>> no_longmode handled by just hanging the machine. Is it enough for
>no_la57
>> case too?
>
>The way to handle it is to check it early in the real mode boot code
>when you 
>can still print messages. That is how missing long mode is handled.
>
>-Andi

Yes, and that test should be done automatically.  However, we also check at several later points in case that code is bypassed by the bootloader.
-- 
Sent from my Android device with K-9 Mail. Please excuse my brevity.