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

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Message-ID: <4FD7B1AB.6030708@zytor.com>
Date:	Tue, 12 Jun 2012 14:16:27 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Brandon Falk <bfalk@...ozolabs.com>
CC:	linux-kernel@...r.kernel.org
Subject: Re: [question] x86/x86_64 boot process

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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