文件列表:

.task08.ko.cmd (332, 2020-08-13)
.task08.mod.o.cmd (48881, 2020-08-13)
.task08.o.cmd (54140, 2020-08-13)
.tmp_versions/ (0, 2020-08-13)
.tmp_versions/task08.mod (92, 2020-08-13)
0001-Adding-eudyptula-to-EXTRAVERSION.patch (534, 2020-08-13)
0001-Coding-style-problem-fixed.patch (1180, 2020-08-13)
c-Fixed-a-brace-coding-style-issue.patch (927, 2020-08-13)
2007d/ (0, 2020-08-13)
2007d/1/ (0, 2020-08-13)
2007d/1/repro (32008, 2020-08-13)
2007d/1/repro.c (36446, 2020-08-13)
2007d/1/sources (78, 2020-08-13)
Makefile (200, 2020-08-13)
Module.symvers (0, 2020-08-13)
cbridge/ (0, 2020-08-13)
cbridge/1007d/ (0, 2020-08-13)
cbridge/1007d/1/ (0, 2020-08-13)
cbridge/1007d/1/1.c (2721, 2020-08-13)
cbridge/1007d/1/Makefile (152, 2020-08-13)
cbridge/1107d/ (0, 2020-08-13)
cbridge/1107d/1/ (0, 2020-08-13)
cbridge/1107d/1/crashreport (3989, 2020-08-13)
cbridge/1107d/1/output (6972, 2020-08-13)
cbridge/1107d/2/ (0, 2020-08-13)
cbridge/1107d/2/crashlog (12179, 2020-08-13)
cbridge/1107d/2/output (16275, 2020-08-13)
cbridge/1107d/2/repro (32032, 2020-08-13)
cbridge/1107d/2/repro.c (39710, 2020-08-13)
cbridge/1107d/3/ (0, 2020-08-13)
cbridge/1107d/3/.output.swp (16384, 2020-08-13)
cbridge/1107d/3/.swp (61440, 2020-08-13)
cbridge/1107d/3/crashlog (6748, 2020-08-13)
cbridge/1107d/3/diffconfig (173142, 2020-08-13)
cbridge/1107d/3/myconfig (170686, 2020-08-13)
cbridge/1107d/3/output (9948, 2020-08-13)
cbridge/1107d/3/repro (16696, 2020-08-13)
cbridge/1107d/3/repro.c (993, 2020-08-13)
cbridge/1107d/3/syzconfig (177790, 2020-08-13)
... ...

# The Eudyptula Challenge #Instructions Welcome to the Eudyptula Challenge! This "challenge" is a series of Linux kernel programming exercises starting out small, and in the end, if all goes well, you'll be the maintainer of a subsystem, if you so desire. Well, maybe not a maintainer, but you will be qualified enough to point out any problems that your favorite maintainer is causing, and that's actually way more fun than being in charge. All of these tasks will be done through email, and will require you to write, modify, and submit Linux kernel patches and code of all different types. First off, some housekeeping rules. You have been assigned a "unique" id. This id is required when submitting your results, as I (a dumb script) need some way to determine what is going on. So, please, for every email you write to me from now on, use your id in the Subject: line like this: [YOUR_ID] Task 02 results And yes, if you haven't guessed it already, "YOUR_ID" is your unique id. Please don't lose it. I can, through some difficulty, figure it out again, but we really don't want to have to get my human involved in this process, that only slows things down. You should be able to just hit "reply" on the task email and all should be fine, if not, the scripts will notify you. Always send submissions in from this email address, the one that you signed up with, emails from any other address will be silently discarded. If you need to change email addresses in the future, just email me and tell me your existing id (YOUR_ID), your original email address, and your new email address, and it will be changed. When you submit a task, you will receive an autoresponse saying where you are in the queue. If you do not receive this autoresponse, I have not received your task, something went wrong, and it needs to be resent. Secondly, no HTML email, or base64-mime attachments. If you have made it this far, you have successfully sent a non-HTML email, which is wonderful (kids these days...), but for all tasks you can't send base64 attachments, as I don't know what to do with them. Just a "normal" attachment, in text form, is fine, and preferred. If you have problems with this, please consult your email client's documentation on how to do this. Thirdly, don't use Gmail or Microsoft Exchange for this set of tasks. Yes, it can be done, but it's really hard, and you really have to know what you are doing. If you get back "I can't understand this response, please try again" message, you might want to switch to a different email client / server and try it again, and notify me of your email address change. Ah, now you see why you use an id and not an email address, we didn't just fall off of the turnip truck yesterday. Fourthly, this challenge is meant to be done over a period of time. Don't rush things, there's no hurry, I'm not going anywhere, and neither are you. So sit back, take your time, and enjoy the process. Life is about the journey, not the end result, as that's the same for everyone. Responses to submissions can sometimes take a few days, or weeks, or they can be a few minutes, depending on the load of the system. There are many thousands of people currently taking this challenge and the scripts get easily backlogged at times. If you ever feel that you missed an email, just ask, and research will be done to see what happened. Sometimes new task emails do get delayed, but it should only be an hour or so, never more than a day to get a new task once you have completed one. If you have not received a new task within a day of a task being marked as completed, please send a reminder email to find out what went wrong. Fifth, as stated on the challenge's home page, please do your work on your own. A number of participants have, in the past, posted the answers to the tasks on github and other public code sites. This instantly caused their solutions to be copied and submitted as answers from other people. I'm sure you don't want to have others copy your hard work. Doing these challenges does not mean you cannot research and try to find out how to do the tasks from existing kernel code and documentation. You are expected to do that. When you do copy code or scripts, please be sure to properly attribute where you copied it from, otherwise I am going to just assume you are trying to pass it off as your own work, which is not a good thing at all. If you are found to have posted your code publicly, or asked for help in public locations, or copied code from public locations without properly attributing it, or tried to cheat or fake challenge results in any way, you will be removed from the challenge instantly. In short, do your own work, and keep it to yourself. Finally, if you have any questions about a task, or need help with something, feel free to ask. I'll alert my human that something is going on, and they will get back to you in a few days with answers. Expect a follow-on email from this with your first task. Responses to tasks might take a few days, depending on the load on my system, and any nasty bugs that show up. Remember the fourth point again, you'll need to keep that in mind during this. As the Big Penguin says, "Have fun!" This is Task 01 of the Eudyptula Challenge ------------------------------------------ Write a Linux kernel module, and stand-alone Makefile, that when loaded prints to the kernel debug log level, "Hello World!" Be sure to make the module able to be unloaded as well. The Makefile should be able to build the kernel module against the source of the currently-running kernel as well as being able to accept an arbitrary kernel sources directory from an environment variable. Please show proof of this module being built, and running, in your kernel. What this proof is is up to you. I'm sure you can come up with something. Also be sure to send the kernel module you wrote, along with the Makefile you created to build the module. Remember to use your ID assigned in the Subject: line when responding to this task, so that I can figure out who to attribute it to. You can just respond to the task with the answers and all should be fine. If you forgot, your id is "YOUR_ID". But of course you have not forgotten that yet, you are better than that. This is Task 02 of the Eudyptula Challenge ------------------------------------------ Now that you have written your first kernel module, it's time to take off the training wheels and move on to building a custom kernel. No more distro kernels for you. For this task you must run your own kernel. And use git! Exciting, isn't it? No? Oh, ok... The tasks for this round are: - Download Linus's latest git tree from git.kernel.org (you have to figure out which one is his. It's not that hard, just remember what his last name is and you should be fine.) - Build it, install it, and boot it. You can use whatever kernel configuration options you wish to use, but you must enable CONFIG_LOCALVERSION_AUTO=y. - Show proof of booting this kernel. Bonus points if you do it on a "real" machine, and not a virtual machine (virtual machines are acceptable, but come on, real kernel developers don't mess around with virtual machines, they are too slow. Oh yeah, we aren't real kernel developers just yet. Well, I'm not anyway, I'm just a script...) Again, proof of running this kernel is up to you, I'm sure you can do well. Hint, you should look into the 'make localmodconfig' option, and base your kernel configuration on a working distro kernel configuration. Don't sit there and answer all 1625 different kernel configuration options by hand, even I, a foolish script, know better than to do that! After doing this, don't throw away that kernel, git tree, and configuration file. You'll be using it for later tasks. A working kernel configuration file is a precious thing, all kernel developers have one they have grown and tended to over the years. This is the start of a long journey with yours. Don't discard it like was a broken umbrella, it deserves better than that. Remember to use your ID assigned in the subject line when responding to this task, so that I can figure out who to attribute it to. If you forgot, your id is "YOUR_ID". But why do I repeat myself? Of course you know your id, you made it through the first task just fine with it. This is Task 03 of the Eudyptula Challenge ------------------------------------------ Now that you have your custom kernel up and running, it's time to modify it! The tasks for this round are: - Take the kernel git tree from Task 02 and change the Makefile to modify the EXTRAVERSION field. Do this in a way that the running kernel (after modifying the Makefile, rebuilding, and rebooting) has the characters "-eudyptula" in the version string. - Show proof of booting this kernel. Extra cookies when you provide creative examples, especially if done in interpretive dance at your local pub. - Send a patch that shows the Makefile modified. Do this in a manner that would be acceptable for merging in the kernel source tree. (Hint, read the file Documentation/SubmittingPatches and follow the steps there.) Remember to use your ID assigned in the subject line when responding to this task, so that I can figure out who to attribute it to. If you forgot, your id is "YOUR_ID". Surely I don't need to keep saying this right? I know, _you_ wouldn't forget, but someone else, of course they would, so I'll just leave it here for those "others." This is Task 04 of the Eudyptula Challenge ------------------------------------------ Wonderful job in making it this far. I hope you have been having fun. Oh, you're getting bored, just booting and installing kernels? Well, time for some pedantic things to make you feel that those kernel builds are actually fun! Part of the job of being a kernel developer is recognizing the proper Linux kernel coding style. The full description of this coding style can be found in the kernel itself, in the Documentation/CodingStyle file. I'd recommend going and reading that right now. It's pretty simple stuff, and something that you are going to need to know and understand. There is also a tool in the kernel source tree in the scripts/ directory called checkpatch.pl that can be used to test for adhering to the coding style rules, as kernel programmers are lazy and prefer to let scripts do their work for them... Why a coding standard at all? Because of your brain (yes, yours, not mine, remember, I'm just some dumb shell scripts). Once your brain learns the patterns, the information contained really starts to sink in better. So it's important that everyone follow the same standard so that the patterns become consistent. In other words, you want to make it really easy for other people to find the bugs in your code, and not be confused and distracted by the fact that you happen to prefer 5 spaces instead of tabs for indentation. Of course you would never prefer such a thing, I'd never accuse you of that, it was just an example, please forgive my impertinence! Anyway, the tasks for this round all deal with the Linux kernel coding style. Attached to this message are is one kernel module that does not follow the proper Linux kernel coding style rules. Fix this file up, AND fix up the final submission you did for Task 01, and send them back to me as attachments in your response email. Yes, the logic in attached second module is crazy, and probably wrong, but don't focus on that, just look at the patterns here, and fix up the coding style, do not remove lines of code. Oh, and before you think "Ah, but I got the coding style right for Task 01, I already know this stuff!", remember that so far only 10 people, out of over 4000, have gotten the coding style exactly right for their Task 01 module. Yes, you could be one of those people, but the odds are not in your favor. You should look at it again just to be sure. So again, attach 2 files, this one fixed up, and your Task 01 submission. Don't use base64 either, the scripts will instantly reject it, you don't want to get on their bad side. As always, please remember to use your ID in the subject line when responding to this task, so that I can figure out who to attribute it to. And if you forgot (which of course you have not, we've been through all of this before), your id is "YOUR_ID". This is Task 05 of the Eudyptula Challenge ------------------------------------------ Yeah, you survived the coding style mess! Now, on to some "real" things, as I know you are getting bored by these so far. So, two simple tasks this time around: - Take the kernel module you wrote for task 01, and modify it so that when any USB keyboard is plugged in, the module will be automatically loaded by the correct userspace hotplug tools (which are implemented by depmod / kmod / udev / mdev / systemd, depending on what distro you are using.) - Again, provide "proof" this all works. Yes, so simple, and yet, it's a bit tricky. As a hint, go read chapter 14 of the book, "Linux Device Drivers, 3rd edition." Don't worry, it's free, and online, no need to go buy anything. As always, please remember to use your ID, yadda yadda yadda... It's "YOUR_ID" of course. This is Task 06 of the Eudyptula Challenge ------------------------------------------ Nice job with the module loading macros. Those are tricky, but a very valuable skill to know about, especially when running across them in real kernel code. Speaking of real kernel code, let's write some! The tasks this time are: - Take the kernel module you wrote for task 01, and modify it to be a misc char device driver. The misc interface is a very simple way to be able to create a character device, without having to worry about all of the sysfs and character device registration mess. And what a mess it is, so stick to the simple interfaces wherever possible. - The misc device should be created with a dynamic minor number, no need running off and trying to reserve a real minor number for your test module, that would be crazy. - The misc device should implement the read and write functions. - The misc device node should show up in /dev/eudyptula. - When the character device node is read from, your assigned id is returned to the caller. - When the character device node is written to, the data sent to the kernel needs to be checked. If it matches your assigned id, then return a correct write return value. If the value does not match your assigned id, return the "invalid value" error value. - The misc device should be registered when your module is loaded, and unregistered when it is unloaded. - Provide some "proof" this all works properly. As you will be putting your id into the kernel module, of course you haven't forgotten it, but just to be safe, it's "YOUR_ID". This is Task 07 of the Eudyptula Challenge ------------------------------------------ Great work with that misc device driver. Isn't that a nice and simple way to write a character driver? Just when you think this challenge is all about writing kernel code, this task is a throwback to your second one. Yes, that's right, building kernels. Turns out that's what most developers end up doing: tons and tons of rebuilds, not writing new code. Sad, but it is a good skill to know. The task this round is: - Download the linux-next kernel for today. Or tomorrow, just use the latest one. It changes every day so there is no specific one you need to pick. Build it. Boot it. Provide proof that you built and booted it. What is the linux-next kernel? Ah, that's part of the challenge. For a hint, you should read the excellent documentation about how the Linux kernel is developed in Documentation/development-process/ in the kernel source itself. It's a great read, and should tell you all you never wanted to know about what Linux kernel developers do and how they do it. As always, please respond to this challenge with your id. I know you know what it is. I'll not even include it this time, I trust you. Don't make me feel that is a mistake. This is Task 08 of the Eudyptula Challenge ------------------------------------------ We will come back to the linux-next kernel in a later exercise, so don't go and delete that directory, you'll want it around. But enough of building kernels, let's write more code! This task is much like the 06 task with the misc device, but this time we are going to focus on another user/kernel interface, debugfs. It is rumored that the creator of debugfs said that there is only one rule for debugfs use": "There are no rules when using debugfs." So let's take them up on that offer and see how to use it. debugfs should be mounted by your distro in /sys/kernel/debug/. If it isn't, then you can mount it with the line: mount -t debugfs none /sys/kernel/debug/ Make sure it is enabled in your kernel, with the CONFIG_DEBUG_FS option, you will need it for this task. The tasks, in specifics are: - Take the kernel module you wrote for task 01, and modify it to create a debugfs subdirectory called "eudyptula". In that directory, create the virtual file called "id". - This "id" file, operates just like it did for example 06, and uses the same logic there, the file is to be readable and writable by any user. - Submit this task as the first email. - Base your work on this submission, and create a new debugfs file called "jiffies". - This "jiffies" file is to be read-only by any user, and when read, should return the current value of the jiffies kernel timer. - Submit this result as a patch against the first email. - Base your work again on that submission, and create a final debugfs file called "foo". - The file "foo" needs to be writable only by root, but readable by anyone. When writing to it, the value must be stored, up to one page of data. When read, which can be done by any user, the value that is stored in it must be returned. Properly handle the fact that someone could be reading from the file while someone else is writing to it (oh, a locking hint!) - Submit this result as a patch against the second email. - When the module is unloaded, all of the debugfs files are cleaned up, and any memory allocated is freed, for all submissions. - Provide some "proof" this all works in the first email. Again, you are using your id in the code, so you know what it is by now, no need to repeat it again. So, for this task, I expect to see 3 emails, all "linked" somehow, in my mailbox. They should look something like this: [YOUR_ID] Task 08 results ├─>[YOUR_ID] [PATCH 01/02] Task 08: add jiffies file └─>[YOUR_ID] [PATCH 02/02] Task 08: add foo file Or, even better: [YOUR_ID] Task 08 results └─>[YOUR_ID] [PATCH 01/02] Task 08: add jiffies file └─>[YOUR_ID] [PATCH 02/02] Task 08: add foo file Hint, look at using 'git send-email' as a way to send these files out. This is Task 09 of the Eudyptula Challenge ------------------------------------------ Nice job with debugfs. That is a handy thing to remember when wanting to print out some debugging information. Never use /proc/ that is only for processes, use debugfs instead. Along with debugfs, sysfs is a common place to put information that needs to move from the user ... ...

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