1. components
   1. kernel
      1. components
         1. process
            1. components
            2. classfication
         2. memory
            1. components
            2. Address space
            3. Page table
            4. classfication
            5. multi-level page table
            6. Page
            7. MMU
            8. TLB
            9. The buddy system
            10. Slab allocator
            11. classfication
            12. operation
            13. Memory mapping
         3. device & driver
            1. components
            2. device
            3. classfication
            4. block devices
            5. Character devices
            6. Network devices
            7. device file
            8. components
            9. /dev
            10. udevd
            11. Ioctl
            12. major minor number
         4. FS
            1. components
            2. VFS
            3. classfication
            4. tmpfs
            5. ramfs
         5. system call
         6. timming
         7. net
         8. module
         9. caching
         10. data type
             1. components
             2. kobject
   2. buses system
      1. classfication
         1. system bus
         2. extension bus
2. operation
   1. I/O
      1. classfication
         1. Port-mapped I/O
         2. Memory-mapped I/O
3. operation
4. components
5. classfication