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SubjectRe: [PATCH v4] RISC-V: Remove any memblock representing unusable memory area
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On Wed, 07 Oct 2020 14:51:59 PDT (-0700), Atish Patra wrote:
> RISC-V limits the physical memory size by -PAGE_OFFSET. Any memory beyond
> that size from DRAM start is unusable. Just remove any memblock pointing
> to those memory region without worrying about computing the maximum size.
>
> Signed-off-by: Atish Patra <atish.patra@wdc.com>
> Reviewed-by: Mike Rapoport <rppt@linux.ibm.com>
> ---
> Changes from v3->v4:
> 1. Rebased on top of for-next.
> ---
> arch/riscv/mm/init.c | 18 +++++++-----------
> 1 file changed, 7 insertions(+), 11 deletions(-)
>
> diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
> index 4eda1a7e8521..da43c17544c5 100644
> --- a/arch/riscv/mm/init.c
> +++ b/arch/riscv/mm/init.c
> @@ -156,9 +156,8 @@ static void __init setup_initrd(void)
>
> void __init setup_bootmem(void)
> {
> - phys_addr_t mem_size = 0;
> - phys_addr_t total_mem = 0;
> - phys_addr_t mem_start, start, end = 0;
> + phys_addr_t mem_start = 0;
> + phys_addr_t start, end = 0;
> phys_addr_t vmlinux_end = __pa_symbol(&_end);
> phys_addr_t vmlinux_start = __pa_symbol(&_start);
> u64 i;
> @@ -166,21 +165,18 @@ void __init setup_bootmem(void)
> /* Find the memory region containing the kernel */
> for_each_mem_range(i, &start, &end) {
> phys_addr_t size = end - start;
> - if (!total_mem)
> + if (!mem_start)
> mem_start = start;
> if (start <= vmlinux_start && vmlinux_end <= end)
> BUG_ON(size == 0);
> - total_mem = total_mem + size;
> }
>
> /*
> - * Remove memblock from the end of usable area to the
> - * end of region
> + * The maximal physical memory size is -PAGE_OFFSET.
> + * Make sure that any memory beyond mem_start + (-PAGE_OFFSET) is removed
> + * as it is unusable by kernel.
> */
> - mem_size = min(total_mem, (phys_addr_t)-PAGE_OFFSET);
> - if (mem_start + mem_size < end)
> - memblock_remove(mem_start + mem_size,
> - end - mem_start - mem_size);
> + memblock_enforce_memory_limit(mem_start - PAGE_OFFSET);
>
> /* Reserve from the start of the kernel to the end of the kernel */
> memblock_reserve(vmlinux_start, vmlinux_end - vmlinux_start);

This is on fixes. Thanks!

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