riscv: Add mem kernel parameter support
The memblock_enforce_memory_limit() could change the memblock
range, so move the dram_end assignment after it in bootmem_init(),
then support mem= cmdline.
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index 30b2045..3a5190a 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -123,19 +123,40 @@
print_vm_layout();
}
+/*
+ * The default maximal physical memory size is -PAGE_OFFSET,
+ * limit the memory size via mem.
+ */
+static phys_addr_t memory_limit = -PAGE_OFFSET;
+
+static int __init early_mem(char *p)
+{
+ u64 size;
+
+ if (!p)
+ return 1;
+
+ size = memparse(p, &p) & PAGE_MASK;
+ memory_limit = min_t(u64, size, memory_limit);
+
+ pr_notice("Memory limited to %lldMB\n", (u64)memory_limit >> 20);
+
+ return 0;
+}
+early_param("mem", early_mem);
+
static void __init setup_bootmem(void)
{
phys_addr_t vmlinux_end = __pa_symbol(&_end);
phys_addr_t vmlinux_start = __pa_symbol(&_start);
- phys_addr_t dram_end = memblock_end_of_DRAM();
phys_addr_t max_mapped_addr = __pa(~(ulong)0);
+ phys_addr_t dram_end;
#ifdef CONFIG_XIP_KERNEL
vmlinux_start = __pa_symbol(&_sdata);
#endif
- /* The maximal physical memory size is -PAGE_OFFSET. */
- memblock_enforce_memory_limit(-PAGE_OFFSET);
+ memblock_enforce_memory_limit(memory_limit);
/*
* Reserve from the start of the kernel to the end of the kernel
@@ -150,6 +171,7 @@
#endif
memblock_reserve(vmlinux_start, vmlinux_end - vmlinux_start);
+ dram_end = memblock_end_of_DRAM();
/*
* memblock allocator is not aware of the fact that last 4K bytes of
* the addressable memory can not be mapped because of IS_ERR_VALUE
