学习kernel写的一些代码

kernel的内存映射结构

内存布局, 16M以后的内存都没有用到

+----------------+ <-- 0x1000000(16M) (main memory end) | | | | | | +----------------+ <-- 0x400000(4M) (memory buffer end) | | | | +----------------+ <-- 0x100000(1M) (kernel code end, memory buffer start) | | +----------------+ <-- 0x7000 _start (kernel code start) | | +----------------+ <-- 0x6000 stack_bottom, idt/gdt | | +----------------+ <-- 0x5000 stack_top | | +----------------+ <-- 0x4000 paging_table_3 | | +----------------+ <-- 0x3000 paging_table_2 | | +----------------+ <-- 0x2000 paging_table_1 | | +----------------+ <-- 0x1000 paging_table_0 | | +----------------+ <-- 0x00 paging_dir