Re: [Xen-devel] [PATCH 2/7] xen/arm: setup the fixmap in head.S

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Wed, 2012-10-24 at 16:03 +0100, Stefano Stabellini wrote:
> @@ -183,6 +184,16 @@ skip_bss:
>         teq   r12, #0
>         bne   pt_ready
>         
> +       /* console fixmap */
> +       ldr   r1, =xen_fixmap
> +       add   r1, r1, r10            /* r1 := paddr (xen_fixmap) */
> +       mov   r3, #0
> +       lsr   r2, r11, #12
> +       lsl   r2, r2, #12            /* 4K aligned paddr of UART */
> +       orr   r2, r2, #PT_UPPER(DEV_L3)
> +       orr   r2, r2, #PT_LOWER(DEV_L3) /* r2:r3 := 4K dev map including UART 
> */
> +       strd  r2, r3, [r1, #0]       /* Map it in the first fixmap's slot */
> +       
>         /* Build the baseline idle pagetable's first-level entries */
>         ldr   r1, =xen_second
>         add   r1, r1, r10            /* r1 := paddr (xen_second) */
[...]
> @@ -205,12 +216,13 @@ skip_bss:
>       ldr   r4, =start
>       lsr   r4, #18                /* Slot for vaddr(start) */
>       strd  r2, r3, [r1, r4]       /* Map Xen there too */
> +
>  #ifdef EARLY_UART_ADDRESS
> -     ldr   r3, =(1<<(54-32))      /* NS for device mapping */
> -     lsr   r2, r11, #21
> -     lsl   r2, r2, #21            /* 2MB-aligned paddr of UART */
> -     orr   r2, r2, #PT_UPPER(DEV)
> -     orr   r2, r2, #PT_LOWER(DEV) /* r2:r3 := 2MB dev map including UART */
> +     /* xen_fixmap pagetable */
> +     ldr r2, =xen_fixmap
> +     add r2, r2, r10
> +     orr   r2, r2, #PT_UPPER(PT)
> +     orr   r2, r2, #PT_LOWER(PT) /* r2:r3 := paddr (xen_fixmap) */

We should setup the fixmap infrastructure even if !EARLY_UART_ADDRESS,
unless we set it up again later?

As it stands it looks like you setup the generic fixmap mapping iff
EARLY_UART_ADDRESS (second hunk above) but setup the UART mapping within
that unconditionally (first hunk) which is exactly backwards, isn't it ?

Ian.


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