Re: Appendix: multithreating HOWTO ? :)

[Frank Kotler <fbkotler@zytor.com>]

£ukasz wrote:
> thanks for answer, im experiment with system clone ( actualy fork i found in many manuals ) but i dont understand Frakns last sentence
> "Well, they *told* us not to do it that way. :)", to program multiproceses with fork ? Any way is there any way to make share memory for proceses ?

Just a "joke". I meant, using the int 80h (or syscall) interface. We're 
"supposed" to use the C interface.

Like Claudio, I'm a "32-bit guy" - and I don't know how to do 
multithreading even on 32-bit. But I think if you're going to use 64-bit 
registers, you'll have to use 64-bit sys_call numbers, put the 
parameters in regs compatible with the 64-bit ABI, and use "syscall" 
instead of "int 0x80". I don't think what you're doing will work, but 
I'm not equipped to try it.

You can share memory between processes by memmapping a region and 
flagging it MAP_SHARED (sys_fork or even separate executables). I 
*think* for threads, you'd want sys_clone, and all memory would be 
shared(?). I think your issue is going to be keeping your threads from 
read/writing the same memory at the same time. I'm a "single CPU guy", 
too, but I think multi-CPU is going to be "even worse".

I made an example using pthread_create - not that I want to use it 
either, but to see what it does for us. Easier to read the source, I'm 
sure, but no, I ran it in strace. Doing a bunch of "signal related" 
stuff I don't understand. I'm afraid I'm going to have to learn more 
about "signals" before I can proceed with this...

For those of us who need to learn about 64-bit programming, there's a 
tutorial:

<http://www.vikaskumar.org/wiki/index.php?title=X86-64_Tutorial>

Came across this, that looked interesting, too:

<http://milw0rm.org/papers/110>

Best,
Frank




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