[PATCH] arm64: override early_init_dt_add_memory_arch()

[Rob Herring]

On Wed, Jul 29, 2015 at 11:14 AM, Ard Biesheuvel
<ard.biesheuvel at linaro.org> wrote:
> Override the __weak early_init_dt_add_memory_arch() with our own
> version. This allows us to relax the imposed restrictions at memory
> discovery time, and clip the memory we will not able to address in
> a single go at mapping time.

This doesn't really explain what is the problem you are solving.

> So copy the generic original, but only retain the check against
> regions whose sizes become zero when clipped to page alignment.
>
> The clipping against the maximum size of the linear region has been
> moved to arm64_memblock_init().

IIRC, the checks in early_init_dt_add_memory_arch came from the arm64
version of it. If you now want to remove them, then I'm okay removing
them from the weak function (assuming my memory is correct). None of
this seems architecture specific to me. Perhaps memblock needs handle
the clipping itself. The arch sets the limits, DT provides the raw
memory ranges, and then memblock sorts out the actual memory blocks.

Rob

>
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel at linaro.org>
> ---
>  arch/arm64/mm/init.c | 35 +++++++++++++++++++++++++++++++++++
>  1 file changed, 35 insertions(+)
>
> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
> index ad87ce826cce..76a624611939 100644
> --- a/arch/arm64/mm/init.c
> +++ b/arch/arm64/mm/init.c
> @@ -158,6 +158,25 @@ early_param("mem", early_mem);
>
>  void __init arm64_memblock_init(void)
>  {
> +       /*
> +        * Remove the memory that we will not be able to cover
> +        * with the linear mapping.
> +        */
> +       const s64 linear_region_size = -(s64)PAGE_OFFSET;
> +
> +       if (memblock_start_of_DRAM() < memstart_addr) {
> +               pr_warn("Ignoring memory below PHYS_OFFSET (0x%012llx - 0x%012llx)\n",
> +                       (u64)memblock_start_of_DRAM(), memstart_addr - 1);
> +               memblock_remove(0, memstart_addr);
> +       }
> +
> +       if (memstart_addr + linear_region_size < memblock_end_of_DRAM()) {
> +               pr_warn("Ignoring memory outside of linear range (0x%012llx - 0x%012llx)\n",
> +                       memstart_addr + linear_region_size,
> +                       (u64)memblock_end_of_DRAM() - 1);
> +               memblock_remove(memstart_addr + linear_region_size, ULLONG_MAX);
> +       }
> +
>         memblock_enforce_memory_limit(memory_limit);
>
>         /*
> @@ -374,3 +393,19 @@ static int __init keepinitrd_setup(char *__unused)
>
>  __setup("keepinitrd", keepinitrd_setup);
>  #endif
> +
> +void __init early_init_dt_add_memory_arch(u64 base, u64 size)
> +{
> +       if (!PAGE_ALIGNED(base)) {
> +               if (size < PAGE_SIZE - (base & ~PAGE_MASK)) {
> +                       pr_warn("Ignoring memory block 0x%llx - 0x%llx\n",
> +                               base, base + size);
> +                       return;
> +               }
> +               size -= PAGE_SIZE - (base & ~PAGE_MASK);
> +               base = PAGE_ALIGN(base);
> +       }
> +       size &= PAGE_MASK;
> +
> +       memblock_add(base, size);
> +}
> --
> 1.9.1
>
>
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