linux-kernel - Re: [PATCH] reserve_early end-of-conventional-memory to 1MB

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Message-ID: <47C3053D.5060504@zytor.com>
Date:	Mon, 25 Feb 2008 10:13:17 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Alexander van Heukelum <heukelum@...lshack.com>
CC:	Ingo Molnar <mingo@...e.hu>,
	Alexander van Heukelum <heukelum@...tmail.fm>,
	Andi Kleen <ak@...e.de>, Thomas Gleixner <tglx@...utronix.de>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] reserve_early end-of-conventional-memory to 1MB

Alexander van Heukelum wrote:
> 
>  arch/x86/kernel/head64.c |   45 +++++++++++++++++++++++++++------------------
>  1 files changed, 27 insertions(+), 18 deletions(-)
> 
> diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
> index 38f32e7..b684552 100644
> --- a/arch/x86/kernel/head64.c
> +++ b/arch/x86/kernel/head64.c
> @@ -49,33 +49,42 @@ static void __init copy_bootdata(char *real_mode_data)
>  	}
>  }
>  
> -#define EBDA_ADDR_POINTER 0x40E
> +#define BIOS_EBDA_SEGMENT 0x40E
> +#define BIOS_LOWMEM_KILOBYTES 0x413
>  

Linus has specific comments in the 32-bit code that states we do not 
want to use address 0x413 for anything - if nothing else because it's 
often lowered when there is boottime code involved like CD-ROM booting 
or PXE.

Either way, the code should be shared between 32 and 64 bits.  There is 
nothing bitsize-specific about it!

	-hpa
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