linux-kernel - Re: [question] x86/x86

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Message-ID: <CAK9+cJX9dSf0H9_W-HjQK3t6DUVtQnvfd-+e_hTUYTuNXnWT=A@mail.gmail.com>
Date:	Tue, 12 Jun 2012 17:20:49 -0400
From:	Brandon Falk <bfalk@...ozolabs.com>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: [question] x86/x86_64 boot process

It's currently only for learning purposes, and I will change loading
from 0x90000. Thanks for the help, now that I know that I'm
responsible for loading the protected-mode code, I know what to do
next.

On Tue, Jun 12, 2012 at 5:16 PM, H. Peter Anvin <hpa@...or.com> wrote:
> On 06/12/2012 02:14 PM, Brandon Falk wrote:
>> All I really see related to the post-setup stage is:
>>
>> 'The 32-bit (non-real-mode) kernel starts at offset (setup_sects+1)*512
>> in the kernel file (again, if setup_sects == 0 the real value is 4.)
>> It should be loaded at address 0x10000 for Image/zImage kernels and
>> 0x100000 for bzImage kernels.'
>>
>> I've read this document a few times, and it doesn't seem to mention if
>> the kernel assists in loading. Do I have to load up the whole
>> protected-mode kernel? Just the first few sectors? I guess that's what
>> I'm trying to figure out, and I feel the boot.txt has not answered
>> that for me.
>>
>
> I would also strongly discourage you from writing a new bootloader if
> you can avoid it.  You *certainly* want to avoid the use of the fixed
> 0x90000 address, that is a decade obsolete.
>
>        -hpa
>
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