Re: [Xen-devel] [PATCH 4/7] arm: map device tree blob in initial page tables

[Tim Deegan <tim@xxxxxxx>]

At 19:15 +0000 on 03 Feb (1328296512), David Vrabel wrote:
> From: David Vrabel <david.vrabel@xxxxxxxxxx>
> 
> Add a 1:1 mapping for the device tree blob in the initial page tables.
> This will allow the DTB to be parsed for memory information prior to
> setting up the real page tables.
> 
> Signed-off-by: David Vrabel <david.vrabel@xxxxxxxxxx>
> ---
>  xen/arch/arm/head.S |    5 +++++
>  1 files changed, 5 insertions(+), 0 deletions(-)
> 
> diff --git a/xen/arch/arm/head.S b/xen/arch/arm/head.S
> index 9951f37..8385481 100644
> --- a/xen/arch/arm/head.S
> +++ b/xen/arch/arm/head.S
> @@ -202,6 +202,11 @@ hyp:
>       add   r4, r4, #8
>       strd  r2, r3, [r1, r4]       /* Map it in the fixmap's slot */
>  #endif
> +     mov   r3, #0x0
> +     orr   r2, r8, #0xe00
> +     orr   r2, r2, #0x07d
> +     mov   r4, r8, lsr #18        /* Slot for (r8 == atag_paddr) */
> +     strd  r2, r3, [r1, r4]       /* Map DTB there */

It might be better to map the DTB at a fixed VA (say, the next
second-level slot up from the fixmap one) so we don't have to worry
about the DTB's PA clashing with Xen's VAs.

Tim.

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