[Linux] Linux内核环境下如何申请大块内存?

void* x_bootmem = NULL;
EXPORT_SYMBOL(x_bootmem);
unsigned long x_bootmem_size = 0;
EXPORT_SYMBOL(x_bootmem_size);
static int __init x_bootmem_setup(char *str)
{
    x_bootmem_size = memparse(str, &str);
    x_bootmem = alloc_bootmem(x_bootmem_size);
    printk("Reserved %lu bytes from %p for x\n", x_bootmem_size, x_bootmem);
    return 1;
}
__setup("x-bootmem=", x_bootmem_setup);