From 7241838b4cecefb32bad4698e748fc31d008d94d Mon Sep 17 00:00:00 2001 From: Frans Kaashoek Date: Tue, 20 Aug 2019 20:23:18 -0400 Subject: Move labs into 6.828 repo. The lab text isn't dependent on specific xv6 code. Lab submission instructions etc. are likely going to be more MIT 6.828 specific. --- labs/xv6.html | 238 ---------------------------------------------------------- 1 file changed, 238 deletions(-) delete mode 100644 labs/xv6.html (limited to 'labs/xv6.html') diff --git a/labs/xv6.html b/labs/xv6.html deleted file mode 100644 index 13d581e..0000000 --- a/labs/xv6.html +++ /dev/null @@ -1,238 +0,0 @@ - - -Lab: xv6 - - - - -

Lab: xv6

- -This lab makes you familiar with xv6 and its system calls. - -

Boot xv6

- -

Login to Athena (e.g., ssh -X athena.dialup.mit.edu) and attach the course -locker: (You must run this command every time you log in; or add it to your -~/.environment file.) - -

-$ add -f 6.828
-
- -

Fetch the xv6 source: - -

-$ mkdir 6.828
-$ cd 6.828
-$ git clone git://github.com/mit-pdos/xv6-riscv.git
-Cloning into 'xv6-riscv'...
-...
-$
-
- -

XXX pointer to an update tools page - -

Build xv6 on Athena: -

-$ cd xv6-public
-$ makeriscv64-linux-gnu-gcc    -c -o kernel/entry.o kernel/entry.S
-riscv64-linux-gnu-gcc -Wall -Werror -O -fno-omit-frame-pointer -ggdb -MD -mcmodel=medany -ffreestanding -fno-common -nostdlib -mno-relax -I. -fno-stack-protector -fno-pie -no-pie   -c -o kernel/start.o kernel/start.c
-...
-$ make qemu
-...
-mkfs/mkfs fs.img README user/_cat user/_echo user/_forktest user/_grep user/_init user/_kill user/_ln user/_ls user/_mkdir user/_rm user/_sh user/_stressfs user/_usertests user/_wc user/_zombie user/_cow 
-nmeta 46 (boot, super, log blocks 30 inode blocks 13, bitmap blocks 1) blocks 954 total 1000
-balloc: first 497 blocks have been allocated
-balloc: write bitmap block at sector 45
-qemu-system-riscv64 -machine virt -kernel kernel/kernel -m 3G -smp 3 -nographic -drive file=fs.img,if=none,format=raw,id=x0 -device virtio-blk-device,drive=x0,bus=virtio-mmio-bus.0
-hart 0 starting
-hart 2 starting
-hart 1 starting
-init: starting sh
-$
-
- -

-If you type ls at the prompt, you should output similar to the following: -

-$ ls
-.              1 1 1024
-..             1 1 1024
-README         2 2 2181
-cat            2 3 21024
-echo           2 4 19776
-forktest       2 5 11456
-grep           2 6 24512
-init           2 7 20656
-kill           2 8 19856
-ln             2 9 19832
-ls             2 10 23280
-mkdir          2 11 19952
-rm             2 12 19936
-sh             2 13 38632
-stressfs       2 14 20912
-usertests      2 15 106264
-wc             2 16 22160
-zombie         2 17 19376
-cow            2 18 27152
-console        3 19 0
-
-These are the programs/files that mkfs includes in the -initial file system. You just ran one of them: ls. - -

sleep

- -

Implement the UNIX program sleep for xv6; your sleep should pause - for a user-specified number of ticks. - -

Some hints: -

- -

Run the program from the xv6 shell: - 

-      $ make qemu
-      ...
-      init: starting sh
-      $ sleep 10
-      (waits for a little while)
-      $
-
- -

Optional: write an uptime program that prints the uptime in terms - of ticks using the uptime system call. - -

pingpong

- -

Write a program that uses UNIX system calls to ``ping-pong'' a - byte between two processes over a pair of pipes, one for each - direction. The parent sends by writing a byte to fd[1] and - the child receives it by reading from fd[0]. After - receiving a byte from parent, the child responds with its own byte - by writing to fd[1], which the parent then reads. - -

Some hints: -

- -

primes

- -

Write a concurrent version of prime sieve using pipes. This idea - is due to Doug McIlroy, inventor of Unix pipes. The picture - halfway down the page - and the text surrounding it explain how to do it. - -

Your goal is to use pipe and fork to set up - the pipeline. The first process feeds the numbers 2 through 35 - into the pipeline. For each prime number, you will arrange to - create one process that reads from its left neighbor over a pipe - and writes to its right neighbor over another pipe. Since xv6 has - limited number of file descriptors and processes, the first - process can stop at 35. - -

Some hints: -

- -

find

- -

Write a simple version of the UNIX find program: find all the files - in a directory tree whose name matches a string. For example if the - file system contains a file a/b, then running find as - follows should produce: - 

-    $ find . b
-    ./a/b
-    $
-
- -

Some hints: -

- -

Optional: support regular expressions in name matching. Grep has some - primitive support for regular expressions. - -

xargs

- -

Write a simple version of the UNIX xargs program: read lines from - standard in and run a command for each line, supplying the line as - arguments to the command. The following example illustrates xarg's - behavior: - 

-    $ xargs echo bye
-    hello too
-    bye hello too
-    
-    $
-
- Note that the command here is "echo bye" and the additional - arguments are "hello too", making the command "echo bye hello too", - which outputs "bye hello too". - -

xargs and find combine well: - 

-    find . b | xargs grep hello
-
- will run "grep hello" on each file named b in the directories below ".". - -

Some hints: -

- -

Optional: modify the shell

- -There are endless ways in which the shell could be extended. Here are -some suggestions: - - - - - - - -- cgit v1.2.3