MAXMEM
mem_limit = MAXMEM;
# define KEXEC_SOURCE_MEMORY_LIMIT (MAXMEM-1)
# define KEXEC_DESTINATION_MEMORY_LIMIT (MAXMEM-1)
# define KEXEC_CONTROL_MEMORY_LIMIT (MAXMEM-1)
#define MAXMEM_PFN PFN_DOWN(MAXMEM)
#define ptr_ok(x) ((x) > PAGE_OFFSET && (x) < PAGE_OFFSET + MAXMEM)
# define MAX_ARCH_PFN MAXMEM>>PAGE_SHIFT
if (physaddr >= MAXMEM || read_cr3_pa() != __pa_nodebug(early_top_pgt))
printk(KERN_WARNING "Warning only %ldMB will be used.\n", MAXMEM>>20);
kasan_mem_to_shadow((void *)PAGE_OFFSET + MAXMEM),
limit = MAXMEM / PAGE_SIZE;
maxmem_pages = EXTRA_MEM_RATIO * min(ini_nr_pages, PFN_DOWN(MAXMEM));