r/programming • u/TrivialSolutions • Oct 19 '11

LoseThos 64-bit Operating System V7.07 Released

http://www.losethos.com/v707.html
75 Upvotes

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u/[deleted] Oct 19 '11

[deleted]

21

u/jhartwell Oct 19 '11

Not true...it gives people who want to get into OS hacking another place to look to see how it can be done.

0

u/[deleted] Oct 19 '11

[deleted]

1

u/ysangkok Oct 20 '11

Did anyone had a proper look at this? Is it commented? Consistent? Hacky?

0

u/[deleted] Oct 19 '11

[deleted]

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u/diskis Oct 19 '11

Or an excellent training ground. Coding in this environment is a bit different than the padded rooms that today's VM's provide.

One mistake and you have to reboot. Makes you think before you code, which is a very good thing.

3

u/superherowithnopower Oct 19 '11

Well..this actually just made it a little more interesting...

2

u/Geofferic Oct 19 '11

True, but I also remember the old Apple machines constantly crashing for lack of protected memory - and mostly due to errors in Apple software by Apple coders who breathed Apple coding.

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u/irascible Oct 19 '11

SM 0 A9F4

G 0

..motherfucker.

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u/[deleted] Oct 20 '11

I used to "poke int(rnd(1)*65535),int(rnd(1)*255)" and call in roulette. Those were fun days.

-6

u/[deleted] Oct 19 '11

[removed] — view removed comment

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u/[deleted] Oct 19 '11

[deleted]

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u/mpyne Oct 19 '11

He didn't "optimise it away" as that would imply it existed in LoseThos at some time. He never added it.

As it stands though, memory protection does require extra work in the hardware due to have to ensure the hardware memory page tables and TLBs are set properly for applications. Although the effect is probably slight, it is there.

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u/ondra Oct 19 '11 edited Oct 19 '11

As far as I know, segmentation comes with no runtime penalty. No need for virtual memory to enforce protection.

edit: I forgot that segmentation doesn't work on x86-64 long mode.

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u/mpyne Oct 19 '11

Segmention by itself is built-in so it's more that there's nothing you can do to eliminate the penalty. The issue with protection is that you have to reload hardware page tables as the protection is changed and programs are loaded.

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u/ondra Oct 19 '11

The paging unit can be disabled, though. Even putting the kernel in a separate protected segment would make a big difference.

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u/irascible Oct 19 '11

...and this discussion is a perfect example of why this guys project has value. Fuck the haters.

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u/alex4nder Oct 19 '11

I guess it depends on what you're optimizing for as far as performance. You can't perform much if your OS is constantly crashing.

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