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

From: hpa
Date: Wed Nov 29 2017 - 16:10:56 EST


On November 29, 2017 12:58:15 PM PST, Andi Kleen <ak@xxxxxxxxxxxxxxx> 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.
--
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