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Subject[PATCH v3] RISC-V: Remove any memblock representing unusable memory area
Date
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 v2->v3
Updated comment as per Mike's suggestion.
---
arch/riscv/mm/init.c | 15 +++++----------
1 file changed, 5 insertions(+), 10 deletions(-)

diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index ca03762a3733..564e0be677b7 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -146,8 +146,6 @@ static phys_addr_t dtb_early_pa __initdata;
void __init setup_bootmem(void)
{
struct memblock_region *reg;
- phys_addr_t mem_size = 0;
- phys_addr_t total_mem = 0;
phys_addr_t mem_start, end = 0;
phys_addr_t vmlinux_end = __pa_symbol(&_end);
phys_addr_t vmlinux_start = __pa_symbol(&_start);
@@ -155,21 +153,18 @@ void __init setup_bootmem(void)
/* Find the memory region containing the kernel */
for_each_memblock(memory, reg) {
end = reg->base + reg->size;
- if (!total_mem)
+ if (!mem_start)
mem_start = reg->base;
if (reg->base <= vmlinux_start && vmlinux_end <= end)
BUG_ON(reg->size == 0);
- total_mem = total_mem + reg->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);
--
2.25.1
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