[PATCH v2 1/7] of/fdt: make memblock minimum physical address arch configurable

[mark.rutland@arm.com (Mark Rutland)]

On Wed, Sep 23, 2015 at 01:37:37AM +0100, Ard Biesheuvel wrote:
> By default, early_init_dt_add_memory_arch() ignores memory below
> the base of the kernel image since it won't be addressable via the
> linear mapping. However, this is not appropriate anymore once we
> decouple the kernel text mapping from the linear mapping, so archs
> may want to drop the low limit entirely. So allow the minimum to be
> overridden by setting MIN_MEMBLOCK_ADDR.
> 
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>

As it's analagou to MAX_MEMBLOCK_ADDR, this makes sense to me.

FWIW:

Acked-by: Mark RUtland <mark.rutland@arm.com>

Mark.

> ---
>  drivers/of/fdt.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
> index 6e82bc42373b..5e7ef800a816 100644
> --- a/drivers/of/fdt.c
> +++ b/drivers/of/fdt.c
> @@ -967,13 +967,16 @@ int __init early_init_dt_scan_chosen(unsigned long node, const char *uname,
>  }
>  
>  #ifdef CONFIG_HAVE_MEMBLOCK
> +#ifndef MIN_MEMBLOCK_ADDR
> +#define MIN_MEMBLOCK_ADDR	__pa(PAGE_OFFSET)
> +#endif
>  #ifndef MAX_MEMBLOCK_ADDR
>  #define MAX_MEMBLOCK_ADDR	((phys_addr_t)~0)
>  #endif
>  
>  void __init __weak early_init_dt_add_memory_arch(u64 base, u64 size)
>  {
> -	const u64 phys_offset = __pa(PAGE_OFFSET);
> +	const u64 phys_offset = MIN_MEMBLOCK_ADDR;
>  
>  	if (!PAGE_ALIGNED(base)) {
>  		if (size < PAGE_SIZE - (base & ~PAGE_MASK)) {
> -- 
> 1.9.1
>