From mboxrd@z Thu Jan  1 00:00:00 1970
From: Tim Deegan <tim@xen.org>
Subject: Re: [PATCH v2] xen/arm: build as zImage
Date: Fri, 23 Nov 2012 18:58:43 +0000
Message-ID: <20121123185843.GD97222@ocelot.phlegethon.org>
References: <alpine.DEB.2.02.1211231715130.13749@kaball.uk.xensource.com>
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To: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Cc: Anthony Perard <anthony.perard@citrix.com>, xen-devel@lists.xensource.com, Ian Campbell <Ian.Campbell@citrix.com>
List-Id: xen-devel@lists.xenproject.org

At 18:04 +0000 on 23 Nov (1353693893), Stefano Stabellini wrote:
> The zImage format is extremely simple: it only consists of a magic
> number and 2 addresses in a specific position (see
> http://www.simtec.co.uk/products/SWLINUX/files/booting_article.html#d0e309).
> 
> Some bootloaders expect a zImage; considering that it doesn't cost us
> much to build Xen compatible with the format, make it so.
> 
> Changes in v2:
> - code style;
> - pass 0 a start address.
> 
> Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
> 
> diff --git a/xen/arch/arm/head.S b/xen/arch/arm/head.S
> index 25c4cfe..347ddcf 100644
> --- a/xen/arch/arm/head.S
> +++ b/xen/arch/arm/head.S
> @@ -22,6 +22,8 @@
>  #include <asm/processor-ca15.h>
>  #include <asm/asm_defns.h>
>  
> +#define ZIMAGE_MAGIC_NUMBER 0x016f2818
> +
>  #define PT_PT  0xe7f /* nG=1, AF=1, SH=10, AP=01, NS=1, ATTR=111, T=1, P=1 */
>  #define PT_MEM 0xe7d /* nG=1, AF=1, SH=10, AP=01, NS=1, ATTR=111, T=0, P=1 */
>  #define PT_DEV 0xe71 /* nG=1, AF=1, SH=10, AP=01, NS=1, ATTR=100, T=0, P=1 */
> @@ -52,6 +54,18 @@
>  	 * or the initial pagetable code below will need adjustment. */
>  	.global start
>  start:
> +
> +	/* zImage magic header, see:
> +	 * http://www.simtec.co.uk/products/SWLINUX/files/booting_article.html#d0e309
> +	 */
> +	.skip 0x20
> +	b     past_zImage

Surely branch _before_ the padding?  

> +	.word ZIMAGE_MAGIC_NUMBER    /* Magic numbers to help the loader */
> +	.word 0x00000000             /* absolute load/run zImage address or
> +	                              * 0 for PiC */
> +	.word _end                   /* zImage end address */

Not (_end - _start)?

Tim.