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Linux Kernel Teaching

linux-kernel-labs.github.io

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Re: Linux Kernel Teaching

#61

Post by saagarjha »

kazinator wrote: post #56
megous wrote: post #52

Earlier quoted context omitted.

In what sense does it overflow? printf("%llx\n", ((long long)0xffffffff Prints: ffffffffffffffff

The idea may be to avoid shifting a 1 into the sign bit, which is undefined behavior. The values in question are being convertd back to loff_t anyway, but that's an implementation-defined conversion rather than undefined behavior. So that is to say, doing the shift in the corresponding unsigned type and then converting to the original signed type is better defined at the language level than just doing the shift in th…

> Well, or maybe not. The one problem there is new changes in GCC which assume that all sorts of things that used to work (and were thus de facto implementation-defined) are no longer happening in programs (because they are undefined behavior, so who would do that?) Thus even if the target hardware has stable two's complement behavior on a left shift that alters the sign of a value, and that has worked fine for years, an updated GCC can suddenly decide that it's okay optimize based on the idea that the program doesn't do such a thing.

Note that Linux compiles with -fwrapv or one of the similar flags that defines overflow to wrap, so this isn’t an issue. I guess this trivializes this patch more, but I figured that they might want the patch anyways in case they ever move off of the flag. (I couldn’t find a uloff_t, so I copied what other code seemed to be doing in this case.)

Re: Linux Kernel Teaching

#62

Post by scoutt »

rtkaratekid wrote: post #30

Started getting into kernel stuff for work. Does anyone have a good idea what kind of market demand there is for kernel devs or similar skill sets? Being new to this I absolutely love it, but have no idea. The resources shared by everyone here are so helpful! I’ve been muddling through by reading the docs, source code, and various messages on the mailing list and... it’s been a little painful.

Very requested for embedded markets (all kind of devices) and you can also specialize into other things, like Android customization.

Re: Linux Kernel Teaching

#63

Post by tzjmetron »

PopeDotNinja wrote: post #46
rtkaratekid wrote: post #30

Started getting into kernel stuff for work. Does anyone have a good idea what kind of market demand there is for kernel devs or similar skill sets? Being new to this I absolutely love it, but have no idea. The resources shared by everyone here are so helpful! I’ve been muddling through by reading the docs, source code, and various messages on the mailing list and... it’s been a little painful.

You might consider going through the git commits, find authors, and investigate where they work.

Finally, a usecase for git blame.

Re: Linux Kernel Teaching

#64

Post by jplayer01 »

ivanfon wrote: post #45

I miss the Eudyptula Challenge [0], I never got around to complementing it. It was a series of 20 challenges to introduce you to Linux kernel development, and it was done entirely over email. I think it's been shut down for a few years now, I'm not sure when or if it'll come back at this point. [0] http://eudyptula-challenge.org/

Aw man. That sounds pretty cool. I guess there isn't anything comparable out there? I'm interested in contributing to the Linux kernel, but it's just so hard to get into it.

Re: Linux Kernel Teaching

#65

Post by dbancajas »

ddevault wrote: post #51
rtkaratekid wrote: post #30

Started getting into kernel stuff for work. Does anyone have a good idea what kind of market demand there is for kernel devs or similar skill sets? Being new to this I absolutely love it, but have no idea. The resources shared by everyone here are so helpful! I’ve been muddling through by reading the docs, source code, and various messages on the mailing list and... it’s been a little painful.

Consistent kernel hackers get hired fast. Focus on a particular subsystem, participate in the community, and contribute regularly - you'll have opportunities in no time.

what would be a typical salary range for 1 year kernel dev + 4-5 years in related experience? let's say BayArea/NY/Austin? I really did like learning about kernel dev before. Might be time to learn again..

Re: Linux Kernel Teaching

#66

Post by ddevault »

dbancajas wrote: post #65
ddevault wrote: post #51

Earlier quoted context omitted.

Consistent kernel hackers get hired fast. Focus on a particular subsystem, participate in the community, and contribute regularly - you'll have opportunities in no time.

what would be a typical salary range for 1 year kernel dev + 4-5 years in related experience? let's say BayArea/NY/Austin? I really did like learning about kernel dev before. Might be time to learn again..

I dunno, maybe around $80K-$100K? In expensive cities, more? At FAANG, more still? A lot of kernel hackers work remotely.

Re: Linux Kernel Teaching

#67

Post by shok3001 »

ddevault wrote: post #66
dbancajas wrote: post #65

Earlier quoted context omitted.

what would be a typical salary range for 1 year kernel dev + 4-5 years in related experience? let's say BayArea/NY/Austin? I really did like learning about kernel dev before. Might be time to learn again..

I dunno, maybe around $80K-$100K? In expensive cities, more? At FAANG, more still? A lot of kernel hackers work remotely.

seems low

Re: Linux Kernel Teaching

#68

Post by ddevault »

shok3001 wrote: post #67
ddevault wrote: post #66

Earlier quoted context omitted.

I dunno, maybe around $80K-$100K? In expensive cities, more? At FAANG, more still? A lot of kernel hackers work remotely.

seems low

Well, it depends on whether or not "4-5 years in related experience" means systems programming or if it means making single-page webapps.

Re: Linux Kernel Teaching

#69

Post by tarruda »

ivanfon wrote: post #45

I miss the Eudyptula Challenge [0], I never got around to complementing it. It was a series of 20 challenges to introduce you to Linux kernel development, and it was done entirely over email. I think it's been shut down for a few years now, I'm not sure when or if it'll come back at this point. [0] http://eudyptula-challenge.org/

It is still possible to find the exercises/answers on github, so anyone can complete the challenge on their own.

Re: Linux Kernel Teaching

#70

Post by jfkebwjsbx »

highspeedmobile wrote: post #59
jfkebwjsbx wrote: post #37

Earlier quoted context omitted.

If you cannot by arsed to learn a few new development tools or workflows, I am sorry but this field is likely to burn you out very soon, be it Linux kernel development, the next shiny GitHub replacement or the new edition of HTML/CSS/whatever. And let's not start about learning the myriad of tools you gotta learn to do in professional Linux kernel development (or any kind of specialized development for that matter).…

This isn't about me or what workflow I can learn. It's really about the entry point for beginners contributing to operating systems in general and making it accessible for them. Not just Linux. On that matter, the barrier for being a long term Linux contributor is still very high and this is from the perspective of outsiders in general. So unless you're working at a company that does professional Linux development wi…

And why should beginners be contributing to the bloody kernel? Why should kernel devs (paid by companies) spend resources on making it easy for beginners?

Here is the thing: kernel development in the most widely used production one is not a trivial thing.

It is like pretending that architecture students should be helped to go work on the next biggest skyscraper as their first project and spend the time of actual architects to make it easy for them.

If you want people to get into kernel development, there are kernels wrote specifically for teaching purposes.

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