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Message-ID: <20130305202229.GW3438@sgi.com>
Date: Tue, 5 Mar 2013 14:22:29 -0600
From: Robin Holt <holt@....com>
To: Yinghai Lu <yinghai@...nel.org>
Cc: Robin Holt <holt@....com>, "H. Peter Anvin" <hpa@...or.com>,
hpa@....com, linux-kernel@...r.kernel.org
Subject: Re: Revert commit 5dcd14ecd4 - breaks EFI boot with SLES11
elilo.efi
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@....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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