Re: [PATCH 4/4] ARM: pbl: MMU: Make it callable multiple times

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

Hello Sascha,

On 2/23/26 9:34 AM, Sascha Hauer wrote:
> mmu_early_enable() is called in barebox_pbl_start() after a call to
> setup_c(). setup_c() clears the BSS which means alloc_pte() starts at
> index zero again when mmu_early_enable() has been called earlier
> already.
> 
> Some boards might want to do exactly that: Call mmu_early_enable()
> earlier to do for example otherwise expensive hashing of xloaded
> binaries.
> 
> Make mmu_early_enable() safe to be called multiple times by moving the
> PTE index out of the BSS.

How about making setup_c() safe for calling multiple times by having it
check and modify a variable in the .data section?

Would that break anything?

Cheers,
Ahmad

> 
> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
> ---
>  arch/arm/cpu/mmu_64.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arm/cpu/mmu_64.c b/arch/arm/cpu/mmu_64.c
> index 7f38473079..2f451b3c91 100644
> --- a/arch/arm/cpu/mmu_64.c
> +++ b/arch/arm/cpu/mmu_64.c
> @@ -86,7 +86,10 @@ static void set_pte_range(unsigned level, uint64_t *virt, phys_addr_t phys,
>  #ifdef __PBL__
>  static uint64_t *alloc_pte(void)
>  {
> -	static unsigned int idx;
> +	static int idx = -1;
> +
> +	if (idx == -1)
> +		idx = 0;
>  
>  	idx++;
>  
> 

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