l4-hackers May 1999

l4-hackers@os.inf.tu-dresden.de

10 participants
20 discussions

Re:
by Michael Hohmuth 31 May '99

31 May '99

"benben xiao" <xiaoxiaoben(a)hotmail.com> writes: > When I see fiasco kernel, I have a simple question: > I don't know > #if 0 > ... > ... > #endif > what do '0' mean there? This is a way to comment out unused code: Everything between "#if 0" and "#endif" is stripped by the preprocessor, and is ignored by the compiler. For more information about the C/C++ preprocessor, please refer to the GNU CPP manual. On most systems, you can browse it with "info cpp". The answer to your particular question is in "info cpp conditional deletion". Michael -- hohmuth(a)innocent.com, hohmuth(a)sax.de http://www.sax.de/~hohmuth/

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Re: Default attributes of tasks/lthreads
by Michael Hohmuth 31 May '99

31 May '99

Robert Kaiser <rob(a)sysgo.de> writes: > The question came up while writing a test suite for a microkernel > we are currently developing. It's API is not identical, but quite > similar to L4's (we would like to run L4Linux on it in the future). If your kernel's API is similar enough: Is there a chance of releasing your test suite as open source? We probably could adapt it to our implementations, and having a test suite for Fiasco and L4/x86 would be very useful. > I can certainly handle this behavior, but I was just wondering > what would be a "clean" design. From what I just learned, there > is in fact a difference between a thread being created and a thread > being re-started into a new context: In the first case, the thread's > scheduling parameters are inherited from the caller, in the latter > case, they retain whatever values they had before. So the caller > of lthread_ex_regs has to be aware of wether the thread already > exists or not. Yes, that's true. What you proposed earlier in this thread (make it possible to set scheduling parameters for not-yet-existing local threads) seems to be somewhat cleaner, but I think the current behavior isn't very difficult to handle; tasks have to keep track of thread states anyway because they manage the allocation of local thread ids themselves. Michael -- hohmuth(a)innocent.com, hohmuth(a)inf.tu-dresden.de http://home.pages.de/~hohmuth/

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Re: Default attributes of tasks/lthreads
by Michael Hohmuth 31 May '99

31 May '99

Robert Kaiser <rob(a)sysgo.de> writes: > I have a question regarding the default scheduling parameters > of newly created tasks and lthreads under L4: > > When I create a new task with the task_new syscall, according > to the L4 manual, that task's lthread 0 starts running immediately. > > But what are it's scheduling parameters (timeslice duration, > priority) in this case ? > > Similarly, when I create a new lthread with lthread_ex_regs, > how are it's scheduling parameters determined ? The parameters are inherited from the creating thread. There usually is a way to change the parameters before the new thread starts running: Use the thread_schedule system call before serving the thread's first page fault. > Also, is it possible to set these parameters for an lthread > that does not yet exist (The manual doesn't explicitly state > this, but the fact that -conceptually- all lthreads of a task > always exist would suggest that this is indeed possible) ? Good question. I think this is not really defined in the manual. The current implementations don't support what you suggest; instead, the scheduling parameters are inherited from the creating thread once the new thread is ``really'' created. Do you have an application where this behavior is a problem? Michael -- hohmuth(a)innocent.com, hohmuth(a)sax.de http://www.sax.de/~hohmuth/

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(no subject)
by benben xiao 31 May '99

31 May '99

Hi Hackers: When I see fiasco kernel, I have a simple question: I don't know #if 0 ... ... #endif what do '0' mean there? Please pardon my poor english! Thank you! ______________________________________________________ Get Your Private, Free Email at http://www.hotmail.com

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Default attributes of tasks/lthreads
by Robert Kaiser 27 May '99

27 May '99

Hi Hackers, I have a question regarding the default scheduling parameters of newly created tasks and lthreads under L4: When I create a new task with the task_new syscall, according to the L4 manual, that task's lthread 0 starts running immediately. But what are it's scheduling parameters (timeslice duration, priority) in this case ? Similarly, when I create a new lthread with lthread_ex_regs, how are it's scheduling parameters determined ? Also, is it possible to set these parameters for an lthread that does not yet exist (The manual doesn't explicitly state this, but the fact that -conceptually- all lthreads of a task always exist would suggest that this is indeed possible) ? Thanks for any response Rob ---------------------------------------------------------------- Robert Kaiser email: rkaiser(a)sysgo.de SYSGO RTS GmbH Carl-Zeiss-Str. 41 phone: (49) 6131 9138-80 D-55129 Mainz / Germany fax: (49) 6131 9138-10

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Re: GMD paper
by Michael Hohmuth 25 May '99

25 May '99

I wrote a few minutes ago: > This paper is now available (along with many other interesting papers > from Jochen) from <URL:http://i30www.ira.uka.de/images/b_publications_on.gif>. ^^^^ Oops, although you probably like GIFs, this one isn't of particular utility. Here's the correct URL: <URL:http://i30www.ira.uka.de/publications/index.html>. Michael -- hohmuth(a)innocent.com, hohmuth(a)inf.tu-dresden.de http://home.pages.de/~hohmuth/

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Re: GMD paper
by Michael Hohmuth 25 May '99

25 May '99

"Adam 'WeirdArms' Wiggins" <awiggins(a)cse.unsw.edu.au writes: > Anyone know where I can get a copy of: > > Jochen Liedtke: > Improved Address Space Switching on Pentium Processors by > Transparently Multiplexing User Address Spaces > (GMD technical report) This paper is now available (along with many other interesting papers from Jochen) from <URL:http://i30www.ira.uka.de/images/b_publications_on.gif>. The URL for the paper you're looking for is <URL:http://i30www.ira.uka.de/publications/pubcat/As-pent.ps>. Michael -- hohmuth(a)innocent.com, hohmuth(a)sax.de http://www.sax.de/~hohmuth/

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Re: Please help me!
by Michael Hohmuth 25 May '99

25 May '99

"benben xiao" <xiaoxiaoben(a)hotmail.com> writes: > Hi; > When I see the file "init.h" in "l4/server/sigma0/src/",I meet a problem. > Although I have know: > #define L4_NORETURN __attribute__((noreturn)) > but I don't understand the function definition: > void init(struct multiboot_info *mbi, unsigned int flag, > l4_kernel_info_t *info) L4_NORETURN; > there why we can use "L4_NORETURN" and what is the effect of > "L4_NORETURN". __attribute__((noreturn)) is an extension supported by the GNU C compiler. It is intended to be used with functions that are not supposed to return. When a function declared with this attribute looks like it returns anyway, the compiler issues a warning. Please consult the Gcc documentation for more details (on most system, you can run "info gcc 'c extensions' 'function attr'"). Michael -- hohmuth(a)innocent.com, hohmuth(a)inf.tu-dresden.de http://home.pages.de/~hohmuth/

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Re: basis of L4-Linux
by Michael Hohmuth 25 May '99

25 May '99

suzukis(a)file.phys.tohoku.ac.jp writes: > uname returned Linux 2.0.21(or 20?) - I remember, L4-Linux > seems to be based old kernel source. But the L4-Linux source > also seems to include something taken from later kernel > source (ex. Configure.help). L4-Linux will be rewritten > from the later Linux kernel (ex. 2.0.36, or 2.2.x)? > Or, will be a branch from the old kernel? We have been working internally on a port of Linux 2.2 to L4, and I'm positive that we can release it ``soon.'' > If asking about L4-Linux is off-topic, please let me know > who/where I could ask about L4-Linux. No, that's fine, you're on-topic. Michael -- hohmuth(a)innocent.com, hohmuth(a)inf.tu-dresden.de http://home.pages.de/~hohmuth/

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Please help me!
by benben xiao 25 May '99

25 May '99

Hi; When I see the file "init.h" in "l4/server/sigma0/src/",I meet a problem. Although I have know: #define L4_NORETURN __attribute__((noreturn)) but I don't understand the function definition: void init(struct multiboot_info *mbi, unsigned int flag, l4_kernel_info_t *info) L4_NORETURN; there why we can use "L4_NORETURN" and what is the effect of "L4_NORETURN". Thank you! ______________________________________________________ Get Your Private, Free Email at http://www.hotmail.com

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l4-hackers May 1999