ARCH_LOW_ADDRESS_LIMIT
#define ACPI_TABLE_UPGRADE_MAX_PHYS ARCH_LOW_ADDRESS_LIMIT
#ifndef ARCH_LOW_ADDRESS_LIMIT
ARCH_LOW_ADDRESS_LIMIT, NUMA_NO_NODE);
io_tlb_default_mem.phys_limit = ARCH_LOW_ADDRESS_LIMIT;
size = memblock_reserved_kern_size(ARCH_LOW_ADDRESS_LIMIT,
ARCH_LOW_ADDRESS_LIMIT);