The well-factored 386

hmm...didn't seem off-topic to me.
Anything about 386 hardware would seem
to be rather closely related to Linux
assembly language programming.
[email protected]

He talks about his x86 emulator he wrote, and people complain to me all the time about his postings.

Nobody ever follows up to any of his postings, he's not even discussing anything, he's just showing how great he thinkgs his x86 emulator is.

linux-kernel is not a bullhorn for people like him to use...

Rick A Hohensee is a clown, a joker, a troll.
One can be amused by his postings, or irritated, or one can ignore them.

No need for any formal action.

You on the other hand threaten with censorship. That is not funny at all.
Censorship would explode in a terrible flamewar.

There is no need for such censorship.

Run your own mailing lists, then you can tell people what is appropriate or not appropriate for list discussions and then decide how to deal with people who ignore such requests to stay on-topic.

Do you accuse me of censoring spammers too? I filter them too. :-)

Off topic postings take people's time, and we have enough traffic with just the on-topic stuff as it is.

If you find pleasure in having to figure out what the regexps are each day needed in order to filter out all the GPL, OSDL, bitkeeper, whatever threads on linux-kernel each and every day on this list that's ok, but most other people do not find this a fun activity at all.

The fact is that people like to abuse linux-kernel because of how large an audience they know it reaches. And frankly, I'm simply not going to tolerate people being jackasses and using linux-kernel as a bullhorn to discuss whatever they think every needs to hear about.

maybe you could add the subscribe/unsubscribe messages (sent to lkml, not majordomo ;) to your filters ... 8-)

best,
Herbert

I didn't realise he was talking about an x86 emulator. I thought he was analyzing real hardware.

The one thing that made it on-topic for me was his quiet suggestion that "forreal" mode interrupts are faster, and that it might, perhaps, be possible to modify a Linux kernel to run in that mode - to take advantage of the faster interrupts.

-- Jamie

That would have to be a kernel for very special use. The "forreal" mode has protection turned off. As far as I know, that means any user process can take over the cpu as if
it was running in kernel mode.

Perhaps useful for some embedded use with only a couple well-tested processes running. Still, a programming error could overwrite kernel memory instead of segfaulting.

Helge Hafting

There are quite a few embedded systems where that is ok, especially if performance is improved.

Also, I am not sure whether paging still works in "forreal" mode. If it does, kernel memory could still be protected. Not well enough for security, but enough to protect against programming errors.

-- Jamie

Paging works even in real mode, afaik. 386es used to emulate "expanded" memory (a simple bank-switching thing for 286) by going into protected mode, change the page tables, then return to real mode with paging still enabled.

So you can probably use paging in "forreal" mode too. I believe you only get the page table's memory mapping capabilities though, I don't think you get protection of "kernel" pages without protection enabled.

You could still "hide" kernel memory by giving userspace another page table, but that means page table switching on each syscall which kills performance worse than interrupt handling in protecxted mode.

Helge Hafting

Yes, that's exactly what I had in mind.

You say that page table switching kills performance, but consider Ingo's latest 64G patches do exactly that, and performance, though degraded, is not too bad.

Whether it's worth doing that would depend on the balance of interrupts vs. syscalls. Some embedded applications are dominated by interrupts, and there are apps which avoid syscalls altogether during the main part of their running.

-- Jamie