留学生考试辅导 ECE 391 Discussion Week 9 – cscodehelp代写
ECE 391 Discussion Week 9
Announcements & Reminders
►MP3.2 due Oct 26th 5:59pm
►No regrades until the Final Demo!
►Extra Credit worth at most 10% of MP3
►Must finish MP3 before you can receive extra credit
►Very difficult to get points (e.g. a start up screen or a fancy BSOD does not count for anything!)
►Start early, plan ahead for CP3! ►Exam 2 on October 28th 7-9PM.
MP3.2 Overview
► Terminal (Keyboard) Driver
► RTC Driver
► Read Only File System Driver
► All your drivers should have read, write, open, close functions (even if they don’t do anything useful right now!)
► These four functions will be mapped to your system call functions in CP3
► Make sure you are using the parameters correctly
► If not specified otherwise, they should return 0 for success, return -1 for failure
Terminal Driver
► Support all alphanumeric keys and symbols (excluding the number pad, home/end section)
► Shift, Ctrl, Alt, Capslock, Backspace and etc.
► Ctrl-L for clear screen and put cursor to upper left corner
► Don’t output special functionality key presses
► Scrolling support
► Scroll to make new space for outputting at the bottom of the screen
► This is NOT page up/down to look at history of commands or the screen history
Terminal (Keyboard) Driver (contd.)
► Keyboard buffer is 128 bytes
► Do NOT extend this limit
► Enter (newline character) is also a character
► Terminal driver is NOT the shell
► Don’t implement a prompt such as “user>” in your driver
► Terminal open() initializes terminal stuff (or nothing), return 0
► Terminal close() clears any terminal specific variables (or do nothing),
return 0
► Terminal read() reads FROM the keyboard buffer into buf, return number of bytes read
► Terminal write() writes TO the screen from buf, return number of bytes written or -1
1. The user program calls terminal write to print “391OS> ” to the screen.
2. The user program wants to get input from the user, so it calls terminal read.
3. The user types “cat frame0.txt” character by character. The keyboard handler writes this to the screen and keyboard buffer.
4. The user presses Enter and terminal_read copies “cat frame0.txt
” from keyboard buffer to buf.
RTC Driver
► RTC open() initializes RTC frequency to 2HZ, return 0
► RTC close() probably does nothing, unless you virtualize RTC, return 0
► RTC read() should block until the next interrupt, return 0 ► NOT for reading the RTC frequency
► RTC write() must be able to change frequency, return 0 or -1 ► New frequency passed through buf ptr or through count?
► Frequencies must be power of 2
► Virtualizing RTC is not required but will be helpful in the future
► This means RTC can be set to any frequency but the program using RTC will not be affected
File System Driver
► Read Appendix A.
► You are given an in-memory filesystem (FS), filesys_img, that is
compiled into the mp3.img and loaded at boot time ► Look in kernel.c to find the address.
► Do NOT try to hardcode the address
► Read-Only
► Nothing to code in the write function, but you still need a write function
► Flat structure
► Only one directory called “.”
► You don’t need to implement a file descriptor yet, but you should read Appendix A and understand it for CP3
File System Structure
File System Driver (files)
►Do NOT assume data blocks are contiguous
►E.g. inode #1 might have its data stored in data blocks 1, 11, 15, 16 ►File open() initialize any temporary structures, return 0
► Uses read_dentry_by_name: name means filename
►File close() undo what you did in the open function, return 0
►File write() should do nothing, return -1
►File read() reads count bytes of data from file into buf
►Uses read_data
File System Driver (directory)
►Directory open() opens a directory file (note file types), return 0
►read_dentry_by_name: name means filename ►Directory close() probably does nothing, return 0
►Directory write() should do nothing, return -1
►Directory read() read files filename by filename, including “.” ►read_dentry_by_index: index is NOT inode number
