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To: linux-kernel@vger.kernel.org
From: "H. Peter Anvin" <hpa@zytor.com>
Subject: Re: lilo, initrd and RAM > 1GB
Date: 1 Jan 2002 17:03:43 -0800
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Followup to:  <3C2F66FF.13BD2A19@xss.co.at>
By author:    Andreas Haumer <andreas@xss.co.at>
In newsgroup: linux.dev.kernel
> 
> To me it looks like lilo get's the initrd start address
> wrong if there is more than 1GB of RAM in the system.
> I haven't found anything in the lilo documentation how to 
> solve this problem. 
> 

The initrd end address should be obtained via the following algorithm:

        # high_addr here is the highest byte that can be occupied by
        # the initrd

	if ( bootproto >= 0x203 ) {
	   high_addr := header->ramdisk_max
        } else {
           high_addr := 0x37ffffff
        }

        high_addr := min(memsize-1, high_addr)


The "magic constant" 0x37ffffff was widely believed to have been
0x3bffffff (which it might have originally been); this value, however,
doesn't work with most kernels.

This is why the ramdisk ceiling needs to be explicitly reported by the
kernel, as is done in the 2.03 boot protocol.

	-hpa
-- 
<hpa@transmeta.com> at work, <hpa@zytor.com> in private!
"Unix gives you enough rope to shoot yourself in the foot."
http://www.zytor.com/~hpa/puzzle.txt	<amsp@zytor.com>
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