SSEG_SIZE
#define LOWMEM_LIMIT (SSEG_SIZE * 2)
#define PHYS_OFFSET_OFFSET (CONFIG_DRAM_BASE & (SSEG_SIZE - 1))
va_pa_offset = read_mmu_msa() & ~(SSEG_SIZE - 1);
unsigned long sseg_size = PFN_DOWN(SSEG_SIZE - PHYS_OFFSET_OFFSET);
write_mmu_msa1(read_mmu_msa0() + SSEG_SIZE);