Date: Tue, 5 Mar 2013 14:22:29 -0600
From: Robin Holt <holt@sgi.com>
To: Yinghai Lu <yinghai@kernel.org>
Cc: Robin Holt <holt@sgi.com>, "H. Peter Anvin" <hpa@zytor.com>, hpa@sgi.com,
        linux-kernel@vger.kernel.org
Subject: Re: Revert commit 5dcd14ecd4 - breaks EFI boot with SLES11
 elilo.efi
Message-ID: <20130305202229.GW3438@sgi.com>
References: <512FC697.3090608@zytor.com>
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 <512FE3AE.4070903@zytor.com>
 <20130305081519.GA19165@sgi.com>
 <9bcd6241-37fd-4ae9-a997-2a5da1eaf997@email.android.com>
 <CAE9FiQV2Wk+yiqR8FnNM_L-p1iQFxDwopRzFWTwm6VCkyrbuoQ@mail.gmail.com>
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On Tue, Mar 05, 2013 at 12:14:56PM -0800, Yinghai Lu wrote:
> On Tue, Mar 5, 2013 at 11:52 AM, Robin Holt <holt@sgi.com> wrote:
> > That fixed it for me.
> >
> > Can you help me understand why sentinel is non-zero?  It looks to me
> > like 3.14 allocates 16kB plus strlen of the command line, zeros it,
> > and then proceeds to fill in fields, some differing from what is in the
> > boot_params structure.  That said, it looks like the sentinel field
> > should remain 0.  I am still trying to understand, but if this patch
> > makes it in, I am happy.
> 
> sentinel is out of setup_header.
> it is 0x1ef. setup_header is from 0x1f1.
> 
> it will be 0xff from arch/x86/boot/header.S for bzImage.
> 
>         .section ".header", "a"
>         .globl  sentinel
> sentinel:       .byte 0xff, 0xff        /* Used to detect broken loaders */
> 
> elilo first copy first page, and get 0x1f1 for setup code sector number.
> then it copies all setup code ( include setup header).
> 
> after that sysdeps_create_boot_params will copy first two pages to bp...
> CopyMem(bp, param_start, 0x2000);

Had not gotten that far in my understanding of elilo.  Now I understand.

Robin
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