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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 @@ -<html> -<head> -<title>Lab: xv6</title> -<link rel="stylesheet" href="homework.css" type="text/css" /> -</head> -<body> - -<h1>Lab: xv6</h1> - -This lab makes you familiar with xv6 and its system calls. - -<h2>Boot xv6</h2> - -<p>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.) - -<pre> -$ add -f 6.828 -</pre> - -<p>Fetch the xv6 source: - -<pre> -$ mkdir 6.828 -$ cd 6.828 -$ git clone git://github.com/mit-pdos/xv6-riscv.git -Cloning into 'xv6-riscv'... -... -$ -</pre> - -<p>XXX pointer to an update tools page - -<p>Build xv6 on Athena: -<pre> -$ 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 -$ -</pre> - -<p> -If you type <tt>ls</tt> at the prompt, you should output similar to the following: -<pre> -$ 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 -</pre> -These are the programs/files that <tt>mkfs</tt> includes in the -initial file system. You just ran one of them: <tt>ls</tt>. - -<h2>sleep</h2> - -<p>Implement the UNIX program sleep for xv6; your sleep should pause - for a user-specified number of ticks. - -<p>Some hints: - <ul> - <li>Look at some of the other programs in <tt>user/</tt> to see - how you can obtain the command-line arguments passed to a program. If the user - forgets to pass an argument, sleep should print an error message. - - <li>The command-line argument is passed as a string; you can convert it to an - integer using <tt>atoi</tt> (see user/ulib.c). - - <li>Use the system call <tt>sleep</tt> (see user/usys.S and kernel/sysproc.c). - - <li>Make sure <tt>main</tt> calls <tt>exit()</tt> in order to exit - your program. - - <li>Add the program to <tt>UPROGS</tt> in Makefile and compile - user programs by typing <tt>make fs.img</tt>. - - </ul> - - <p>Run the program from the xv6 shell: - <pre> - $ make qemu - ... - init: starting sh - $ sleep 10 - (waits for a little while) - $ - </pre> - - <p>Optional: write an uptime program that prints the uptime in terms - of ticks using the <tt>uptime</tt> system call. - -<h2>pingpong</h2> - -<p> 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 <tt>fd[1]</tt> and - the child receives it by reading from <tt>fd[0]</tt>. After - receiving a byte from parent, the child responds with its own byte - by writing to <tt>fd[1]</tt>, which the parent then reads. - -<p>Some hints: - <ul> - <li>Use <tt>pipe</tt> to create a pipe. - <li>Use <tt>fork</tt> to create a child. - <li>Use <tt>read</tt> to read from the pipe, and <tt>write</tt> to write to the pipe. - </ul> - -<h2>primes</h2> - - <p>Write a concurrent version of prime sieve using pipes. This idea - is due to Doug McIlroy, inventor of Unix pipes. The picture - halfway down <a href="http://swtch.com/~rsc/thread/">the page</a> - and the text surrounding it explain how to do it. - - <p>Your goal is to use <tt>pipe</tt> and <tt>fork</tt> 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. - -<p>Some hints: - <ul> - <li>Be careful to close file descriptors that a process doesn't - need, because otherwise your program will run xv6 out of resources - before the first process reaches 35. - - <li>Once the first process reach 35, you should arrange that the - pipeline terminates cleanly (Hint: read will return an end-of-file - when the write-side of the pipe is closed). - </ul> - -<h2>find</h2> - -<p>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 <tt>a/b</tt>, then running find as - follows should produce: - <pre> - $ find . b - ./a/b - $ - </pre> - -<p>Some hints: - <ul> - <li>Look at user/ls.c to see how to read directories. - <li>Use recursion to run find in sub-directories. - <li>Don't recurse into "." and "..". - </ul> - -<p>Optional: support regular expressions in name matching. Grep has some - primitive support for regular expressions. - -<h2>xargs</h2> - -<p>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: - <pre> - $ xargs echo bye - hello too - bye hello too - <ctrl-d> - $ - </pre> - 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". - -<p>xargs and find combine well: - <pre> - find . b | xargs grep hello - </pre> - will run "grep hello" on each file named b in the directories below ".". - -<p>Some hints: - <ul> - <li>Use <tt>fork</tt> and <tt>exec</tt> system call to invoke the - command on each line of input. Use <tt>wait</tt> in the parent - to wait for the child to complete running the command. - <li>Read from stdin a character at the time until the newline - character ('\n'). - <li>kernel/param.h declares MAXARG, which may be useful if you need - to declare an argv. - </ul> - -<h2>Optional: modify the shell</h2> - -There are endless ways in which the shell could be extended. Here are -some suggestions: - -<ul> - -<li>Modify the shell to support wait. - -<li>Modify the shell to support lists of commands, separated by ";" - -<li>Modify the shell to support sub-shells by implementing "(" and ")" - -<li>Modify the shell to allow users to edit the command line - -</ul> - -</body> -</html> - - |