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RE: Critics on L4 (NOT Re: shared memory Beispiel?)
by yuan Darwin-r62832 02 Sep '05

02 Sep '05

Hi, Please see my comments below. -----Original Message----- From: l4-hackers-bounces(a)os.inf.tu-dresden.de [mailto:l4-hackers-bounces@os.inf.tu-dresden.de] On Behalf Of Adam Lackorzynski Sent: Friday, September 02, 2005 7:14 AM To: l4-hackers(a)os.inf.tu-dresden.de Subject: Re: Critics on L4 (NOT Re: shared memory Beispiel?) > Hi, > first, please use a proper quoting style. Your style is very unusual and irritating. First of all, I'd like to say that I won't use your "proper" quoting style, because that's just one of the styles which are used widely. In my mail system, the style which I used is set automatically. & more than 20,000 employees of our company around world are using this. If you don't like it, you don't have to read it. However, because this mail is a reply for you. To make you feel comfortable, I made the style as you want by HAND. Again, as I said before, I'm a junior of L4. However, I have been working in OS fields for many years. So, don't tell me any stupid knowledge & ask any stupid quesiton. On Wed Aug 31, 2005 at 21:00:16 +0800, yuan Darwin-r62832 wrote: > > > >When those features are going to be implemented? > > > > > >Fiasco implements IO Flexpages. Neither Redirectors nor Clans and > > >Chiefs > > >are currently implemented in Fiasco and probably never will. I cannot > > >speak for plans regarding Pistachio. > > >[Darwin Yuan] I didn't read the source code of Fiasco. However, from > >the documents I got from its website, I found that Clans & Chiefs was > >implemented in its kernel ( It might be removed now). But I don't > C&C were never implemented, and will never be, in any kernel. As I said, I didn't the source code of Fiasco, & will never be. Now that the documents declare that, I believed that. Thanks anyway for your telling me this. > think it's a good design that this policy was involved in L4 kernel, > now that L4 claims it's a real microkernel. However, I think those > kind of policies could be implemented outside kernel. Therefore, I > think Redirector is a good mechanism to achieve those kind of > policies. That's why I think redirector is very important for > implementing a flexible system on L4. > So what we have now are inflexible systems? If there isn't any inflexible system, why do we need microkernels? > > >Now that those features are very important for implementing a > > >flexible > > >OS on L4 u-kernel. > > > > > > > >Both redirectors and IO flexpages are not essential to get a system up > >and running. Their purpose is to control and restrict communication > >between threads respectively to prevent a thread from reading / writing > >IO-ports. Feel free to implement those features if you need them. > > > > [Darwin Yuan] Yes, That's true. However, a real system should makes > > peripheral equipment work. IO Fpage is very essential for implementing > > hardware driver. >Not having IO protection doesn't mean you cannot use drivers! Not having IO protection means that everyone >can whack your system because everyone runs with IO privileges, that's it. And you need to do this because >you cannot have drivers otherwise. We lived with that for some time but now we have proper IO protection so everything in fine in this regard. Of course I know we can use drivers by opening IO priviledges for all users. However, providing protection is a very essential responsibility for any secure OS. I'd pleased that you have achieved this. > > >I think L4Ka::Pistachio is more clean & flexible, why Fiasco put so > > >many complicated & inflexible policies inside L4 kernel? > > > > > > > > > Which policies are you referring to? Can you elaborate on these > > >points? > > > >[Darwin Yuan] For example, Clans & Chiefs. Also, I think "Task" is a >That's not the fault of Fiasco, C&C is in the V2 spec. These are different things. And as already mentioned C&C where never implemented >as some clever guys noticed before that there are some problems. Everything I know about Fiasco is from V2 spec & other documents from Fiasco website. Frankly speaking, I don't like that spec. If that spec is the first L4 spec I read, I will definitely lost the interests in researching L4. Fortunately, X2 is the one. > >redundant abstract/concept, "Address Space" is a much better one. By >What's the difference between Task and AS? Task & AS are basically identical. However, when we talk about genenel OS concept, we will say that a Task has its own AS. & may owns some of threads. Even it's hard to figure out the difference, but that's the difference. L4 X2 spec use the AS concept instead of Task, will provide more flexible mechanism. For example, L4 X2 spec allows a non-interrupt thread migrated to another AS. If we use the concept "Task", this mechanism will cause confusion. Because from the point of general OS concept view, a thread transfers between Tasks is a little strange. That's why I think using the term "AS" is a better choice than using "Task". > >"Thread" & "Address Space", L4Ka::Pistachio makes the abstract very > >refined, and allows to construct very flexible system. All together, > >the APIs of X.2 is much better than X.0. >X.2 is the successor of V2/X0 so this is no real surprise. But in which way does the API decide how one's building flexible or inflexible systems? API is the interface provided by OS/kernel to outside. It's the reflection of OS/kernel mechanism. If a OS/kernel don't have a good support for build flexible system, can you easily do it? Another example, if hardware didn't provide MMU, can you easily implement VM? > >Why don't you like the design of L4Linux or do you mean Fiasco? > > > >[Darwin Yuan] Actually, I don't like the APIs & mechanism of Fiasco. > >Now that L4Linux is based on those APIs & mechanism, I don't like this > >version of L4Linux. > Cool. So what would I need to do to make it please you? Actually, you don't need anything. Because L4 x.2 & L4Ka::Pistachio are there. Thanks anyway. Adam -- Adam adam(a)os.inf.tu-dresden.de Lackorzynski http://os.inf.tu-dresden.de/~adam/ _______________________________________________ l4-hackers mailing list l4-hackers(a)os.inf.tu-dresden.de http://os.inf.tu-dresden.de/mailman/listinfo/l4-hackers

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Re: shared memory Beispiel?
by Frank Mehnert 02 Sep '05

02 Sep '05

Hi Mathias, please send questions like this to l4-hackers in every case. Simply because I'm not the only one with knowledge about L4/L4-Userland. The other reason is that other L4 developers might be interested in such questions as well. On Wednesday 31 August 2005 10:03, you wrote: > ich versuche eine L4-Anwendung zu schreiben, die mit shared memory > arbeitet. Konkret soll ein Kernel-Thread in L4Linux-2.6 (ein > Netzwerktreiber-Stub) über den gemeinsamen Speicher mit einem L4-Task > (der ausgelagerte Netzwerktreiber) die zu sendenden, bzw. empfangenen > Rahmen austauschen. Ich hab schon im l4/pkg-Verzeichnis nach etwas > passendem gesucht, doch bin nicht wirklich fündig geworden, wie man dass > nun am Besten macht. > Ich will ja nur ein Stück Speicher fester Größe read/write für zwei > L4-Threads mappen. Muss ich dazu den Dataspacemanager benutzen, oder den > Regionmapper, oder gar l4io? Oder geht das vielleicht doch allein mit > den L4.V2-Systemrufen? I would suggest to use the dataspace manager dm_phys to allocate some memory and to map it into both L4Linux 2.6 and the native L4 task. Mapping into the native L4 task should be no problem as long this task has a region manager (the normal case for L4env tasks) -- simply attach the dataspace to the region manager. To map it into L4Linux 2.6, you have to reserve a range of virtual memory inside the Linux server (Adam, which function should someone use for this?) and then map it into that reserved region via l4dm_map_ds() (see dm_phys manual). Since L4Linux 2.6 makes havy use of L4env functionality, this function is available. Make sure that the whole dataspace is mapped into L4Linux since there is no region manager. Finally, make sure that both tasks have the right to map the dataspace. If the Linux server creates the dataspace it has to share the rights explicitly with the native L4 task with l4dm_share(). A more advanced approach would be to use the DSI (DROPS streaming interface) which is also available at the remote CVS. The DSI provides functions for synchronization between clients accessing the same dataspace. There is the dsi_example package. There might be comments from other people reading this list. > Entschuldige, dass ich Dich mit solch banalen Problemen störe, doch ich > weiß eben nicht, wie man das macht und die Dokumentationen (dm_mem, > dm_phys, L4-Referenzmanual, ...) sind dahingehend nicht gerade > aussagekräftig :/ IMHO there still were some threads about this on l4-hackers (please see http://os.inf.tu-dresden.de/mailman/listinfo/) Frank -- ## Dept. of Computer Science, Dresden University of Technology, Germany ## ## http://os.inf.tu-dresden.de/~fm3 ##

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RE: shared memory Beispiel?
by yuan Darwin-r62832 31 Aug '05

31 Aug '05

Hi L4Ka::Pistachio developers, I have read the source code of L4Ka::Pistachio-0.4. & found that some features defined in L4 eXperimental Kernel Reference Manual Version X.2 Revision 5 hasn't been implemented yet. For example, appoint redirector by SpaceControl, IO port mapping, etc. I tried to checkout the newest source code from CVS, & the CVS server cvs.l4ka.org couldn't be reached. When those features are going to be implemented? Now that those features are very important for implementing a flexible OS on L4 u-kernel. Seems that there are so many differences between L4Ka::Pistachio and Fiasco. Is there a stardard L4 specification? I think L4Ka::Pistachio is more clean & flexible, why Fiasco put so many complicated & inflexible policies inside L4 kernel? BTW, has any OS or system been built on L4Ka::Pistachio? As I know, L4-Linux is built on Fiasco, but I don't like its design. I hope I can get a reference system based on L4Ka::Pistachio. Best Regards, Darwin Yuan -----Original Message----- From: l4-hackers-bounces(a)os.inf.tu-dresden.de [mailto:l4-hackers-bounces@os.inf.tu-dresden.de] On Behalf Of Frank Mehnert Sent: Wednesday, August 31, 2005 4:36 PM To: Mathias Krause Cc: l4-hackers(a)os.inf.tu-dresden.de Subject: Re: shared memory Beispiel? _______________________________________________ l4-hackers mailing list l4-hackers(a)os.inf.tu-dresden.de http://os.inf.tu-dresden.de/mailman/listinfo/l4-hackers

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Re: gcc3.4 problem
by Leon Brits 31 Aug '05

31 Aug '05

Adam, This must be some Ubuntu thing since it compiles fine on a Gentoo box!? Any way now I get "Panic: deceiving ipc"-error after loading the console (l4con) and trying to start "run". Nothing else is loaded (see attachments). Thanks for all your support! Leon

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problem deploying l4env
by Christoph Mueller 25 Aug '05

25 Aug '05

Hello, I tried to build an l4env enabled simple hello world server, but I was not able to deploy it, because the l4env-servers did not start up. (Hello in sigma0-mode did work.) I have attached output from serial console and menu.lst from grub. Thanks, Christoph

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gcc3.4 problem
by Leon Brits 25 Aug '05

25 Aug '05

Hi all, Based on recent posts on this mailing list I decided to also give GCC 3.4 a go and ran into the following error when compiling l4linux-2.4: ljbrits@abc:/home/drops/DROPS/l4linux-2.4 $ make scripts/split-include include/linux/autoconf.h include/config gcc -D__KERNEL__ -I/home/drops/trunk/l4linux-2.4/include -Wall -Wstrict-prototypes -Wno-trigraphs -O2 -fno-strict-aliasing -fno-common -gstabs+ -DLINUX_ON_L4 -I/home/drops/DROPS/l4/include/x86/l4v2 -I/home/drops/DROPS/l4/include/x86 -I/home/drops/DROPS/l4/include -DL4API_l4v2 -pipe -mpreferred-stack-boundary=2 -march=i686 -fno-unit-at-a-time -DKBUILD_BASENAME=main -c -o init/main.o init/main.c init/main.c: In function `init': /home/drops/trunk/l4linux-2.4/include/asm-l4/arch-i386/unistd.h:90: sorry, unimplemented: inlining failed in call to '__SC__open': function body not available init/main.c:105: sorry, unimplemented: called from here /home/drops/trunk/l4linux-2.4/include/asm-l4/arch-i386/unistd.h:89: sorry, unimplemented: inlining failed in call to '__SC__dup': function body not available init/main.c:104: sorry, unimplemented: called from here /home/drops/trunk/l4linux-2.4/include/asm-l4/arch-i386/unistd.h:89: sorry, unimplemented: inlining failed in call to '__SC__dup': function body not available init/main.c:104: sorry, unimplemented: called from here make: *** [init/main.o] Error 1 As I said I installed GCC3.4 on my system (Ubuntu 5.04) and changed all the symlinks in /usr/bin to point to the new installation of gcc and g ++. I made sure that everything was compiling just fine before installing the new compiler. Any suggestions? Thanks Leon

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Interrupt latency in L4Linux
by fabs0028＠free.fr 23 Aug '05

23 Aug '05

Hello, well i 'd like to measure the latency of the interrupts in l4linux, between the moment it is triggered in fiasco and the moment it is aknowledged in the top-halves of linux. Some hints would be greatly appreciated. Thanx for your help. Fabien Chaillou

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Re: l4-hackers Digest, Vol 28, Issue 13
by basant mudalgi 22 Aug '05

22 Aug '05

tanks

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Patches for L4linux
by basant mudalgi 22 Aug '05

22 Aug '05

Hi dont know if this is the right place to send this mail to. I am pretty new to the whole l4 concept. I have been trying to download the l4linux-2.6.12 on my pathetic dial-up connection which is obviously taking longer than expected. i would like to know if there are patches which i can apply to the standard linux (monolithic) kernel to make it an l4linux kernel and save a lot of download time and effort. ie. something like: linux-2.6.xx ----patch----> l4linux-2.6.xx If so where do i find them? If not ...could anyone do the favour? Regards ------------ Basant Mudalgi

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l4linux based distro
by PhilT 19 Aug '05

19 Aug '05

Is L4Linux good enough to be included in a standard Linux distro? I was wondering if anyone was planning to do so? I am trying to compile L4Linux under Ubuntu but am getting lots of error messages during the compile. My lack of knowledge of Linux/L4 etc means it will probably be difficult to ever get this working. Does anyone have pre-compile binaries? Many thanks Rabbit

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RT-Drops : Admission Server
by Arthur Mielimonka 18 Aug '05

18 Aug '05

Hi, when we (Erlangen INF 6) were in Dresden you told us about an Admission Server which assures that periodic realtime-threads can reserve cpu-time with a validation that no over-reservation is made. I didn't find it in the remote-cvs, would you please add it or send it to me? Thanks, Arthur PS: See http://os.inf.tu-dresden.de/papers_ps/steinberg-diplom.pdf , chapter 3.1.3 for the Programming model for Admission Servers

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Via C3 Assertion Failed
by Christoph Mueller 18 Aug '05

18 Aug '05

Hello, I tried to run the demo-CD on my laptop that has a Via C3 CPU. The following error occured: >Assertion failed: '!(*pte & INTEL_PTE_VALID)' > in .../boot/ia32/boot_cpu.cc:450 in function (null) at 00300539 Some more info about the processor: $ cat /proc/cpuinfo: processor : 0 vendor_id : CentaurHauls cpu family : 6 model : 7 model name : VIA Ezra stepping : 8 cpu MHz : 798.007 cache size : 64 KB fdiv_bug : no hlt_bug : no f00f_bug : no coma_bug : no fpu : yes fpu_exception : yes cpuid level : 1 wp : yes flags : fpu de tsc msr cx8 mtrr pge mmx 3dnow bogomips : 1592.52 Is there a way to run DROPS on Via C3 or should i reinstall the energy-intensive Intel Pentium 3? Thanks, Christoph

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Re: Reboot does not work anymore!
by Frank Mehnert 17 Aug '05

17 Aug '05

On Wednesday 17 August 2005 15:48, Leon Brits wrote: > > Should not does any matter. But how do you set the video mode, via GRUB > > vbeset of via --vbemode parameter of l4con? > > grub Hmm. Very strange. When you reboot via the l4con console you most probably mean the pkg/loader/example/run program. Could you please disassemble that binary objdump -ld loader/example/run/OBJ-x86_586-l4v2/run | less and search for pc_reset, right? That function should come from oskit10 and we did not change anything there. Frank -- ## Dept. of Computer Science, Dresden University of Technology, Germany ## ## http://os.inf.tu-dresden.de/~fm3 ##

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Reboot does not work anymore!
by Leon Brits 17 Aug '05

17 Aug '05

Hi all, I've moved to the latest CVS checkout of L4 and L4Env and now the "Reboot Sequence" in the console (Shift-6-6) does not work anymore. It prints the second "rebooting" message and then just hangs. Any suggestions? Thanks Leon NB. It is the first time I am using l4con instead of con.

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c++ stl in l4/pkg/libstdc++
by Bert van Leeuwen 17 Aug '05

17 Aug '05

Hi, Can somebody (Frank?) please give me some pointers on how to replace the STL in l4/pkg/libstdc++ for gcc 3.3.x (i.e. /l4/pkg/libstdc++/lib/src-v3 and l4/pkg/libstdc++/contrib/libstdc++-v3)? It seems to be rather an old version, and I would like to try a newer version to eliminate possible sources of error in my program. I tried just replacing drops/include/c++/3.3 with the STL on my box, but that gave hundreds of compile errors. (My program is hanging sporadically, and everytime I get a backtrace into the hung thread, it is somewhere inside STL list. I cannot reproduce this behaviour in linux, only in L4, so I want to see if replacing the STL with a newer version will help) Thanks, Bert

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prebuilt environment
by Julian Stecklina 16 Aug '05

16 Aug '05

Hello, is there somewhere a prebuilt build environment for Fiasco/L4-Env/ DROPS? My primary development box (and in fact all PCs I own) run FreeBSD and I do not plan to switch to some GNU/Linux which most parts of the build process seem to assume. Even a Linux build would be useful to me, as I could run it using the Linuxulator. Regards, -- Julian Stecklina (Of course SML does have its weaknesses, but by comparison, a discussion of C++'s strengths and flaws always sounds like an argument about whether one should face north or east when one is sacrificing one's goat to the rain god.) -- Thant Tessman

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Re: What happens on timeslice overrun?
by Udo A. Steinberg 15 Aug '05

15 Aug '05

On Mon, 15 Aug 2005 15:17:20 +0200 Rene Wittmann (RW) wrote: RW> > When a thread is preempted (that means it gets involuntarily RW> > descheduled), the remaining time quantum is saved and later RW> > restored when the thread is scheduled again. If the thread RW> > yields its scheduling context (that means it voluntarily RW> > gives it away), the time quantum is no longer available to RW> > the thread. A yield can happen in two ways depending on the RW> > target thread id specified: RW> > RW> > 1) if the target ID is the NIL_ID, then the thread yields its active RW> > scheduling context to noone - the time is effectively gone. This is RW> > what next_reservation does. Note that the kernel checks RW> > the user-specified RW> > ID, to guard against the case where a thread wants to RW> > yield its active RW> > scheduling context and the time quantum on that scheduling RW> > context expires RW> > simultaneously. RW> > RW> > 2) if the target ID is a valid thread ID in the system, then RW> > the action RW> > depends on whether the specified thread is ready to run: RW> > a) if it is, then the current thread donates the current scheduling RW> > context to the specified thread and that thread then becomes the RW> > current thread. This is similar to what happens during RW> > a donating IPC. RW> > RW> > b) if the specified thread is not ready, then the current RW> > scheduling RW> > context is gone, similar to 1) RW> > RW> How can I specify the target ID? When creating the thread? But how? The target thread ID for l4_thread_switch, i.e. the thread to yield to, is a parameter to that system call. The L4 interface (see L4.V2 manual) describes the ABI for x86: The following registers are defined for Fiasco: EAX scheduling context ID ESI low part of the target thread ID After the system call returns, the following registers are defined: EAX return value (0 = success, -1 = failure) ECX low part of remaining time on yielded sched. context (if EAX is 0) EDX high part of remaining time on yielded sched. context (if EAX is 0) You probably need not concern yourself with these low-level details of the L4 ABI - there should be bindings in l4/pkg/l4sys that provide high-level interfaces to l4_thread_switch. -Udo.

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AW: What happens on timeslice overrun?
by Rene Wittmann 15 Aug '05

15 Aug '05

> RW> I have 2 questions on the RT part in DROPS: > RW> > RW> 1.) I have 2 RT working threads, each with 3 timeslices: > RW> Thread 1: period=10ms > RW> ts1=30ms prio1=50 > RW> ts2=10ms prio2=30 > RW> ts3=20ms prio3=50 > RW> > RW> Thread 2: period=10ms > RW> ts1=20ms prio1=40 > RW> ts2=5ms prio2=30 > RW> ts3=10ms prio3=40 > RW> > RW> Assume both threads are ready at the same time. > RW> So thread 1 starts and does its work until it releases the > RW> voluntarily or it's preempted by its preempter-thread. So say it > RW> releases voluntarily after 20ms. > > When you say "it's preempted by its preempter thread", do you > mean the situation when a preempter with a higher priority > than the current thread receives a preemption IPC from the > kernel and thus preempts the current thread? > That's what I meant. The preempter has a higher priority and receives the IPC and thus "tells" (via IPC or via common variable if in same address space) the thread to stop the work. > RW> Who will get the left 10ms? I guess nobody. > > When a thread is preempted (that means it gets involuntarily > descheduled), the remaining time quantum is saved and later > restored when the thread is scheduled again. If the thread > yields its scheduling context (that means it voluntarily > gives it away), the time quantum is no longer available to > the thread. A yield can happen in two ways depending on the > target thread id specified: > > 1) if the target ID is the NIL_ID, then the thread yields its active > scheduling context to noone - the time is effectively gone. This is > what next_reservation does. Note that the kernel checks > the user-specified > ID, to guard against the case where a thread wants to > yield its active > scheduling context and the time quantum on that scheduling > context expires > simultaneously. > > 2) if the target ID is a valid thread ID in the system, then > the action > depends on whether the specified thread is ready to run: > a) if it is, then the current thread donates the current scheduling > context to the specified thread and that thread then becomes the > current thread. This is similar to what happens during > a donating IPC. > > b) if the specified thread is not ready, then the current > scheduling > context is gone, similar to 1) > How can I specify the target ID? When creating the thread? But how? > RW> Or can I assign my left time to a specific thread, say > ts2 of thread > RW> 1, that is has 20ms after recognizing that ts1 was finished 10ms > RW> earlier?I could do with l4_rt_change_timeslice(), but this would > RW> probably not work for the the current period! (or yes?) > > A thread can yield the current scheduling context to another > thread as described in 2a) above. Note that the thread will > yield the current scheduling context (which may not > necessarily be the thread's own active scheduling context). > As an example consider: > A sends a donating IPC to B, now B runs on A's scheduling > context. If B yields to C, then C will run on A's time and B > will not donate its own scheduling context. If the current > scheduling context is in fact the active scheduling context > of the donating thread, then realize that the donating thread > will likely encounter a timeslice overrun soon after the > yield (the donatee will consume the time quantum until it runs out). > If you'd rather avoid that, then the donatee will have to > yield the scheduling context back to the owner (the original > donator) who then has to yield it to noone. > > Changes to the time quantum of a scheduling context are only > visible the next time that scheduling context becomes the > current scheduling context. That means if you change the > current scheduling context, then the change will not be > visible immediately. > OK, that's clear now. > RW> 2.) Consider we have a deadline miss. And we say > RW> l4_rt_next_period(): would it wait for the beginning of the next > RW> (which means: > RW> period 1: deadline miss > RW> period 2: call next period (because we think we're > RW> still in period 1)+ wait to end of period > RW> period 3: normal work) > RW> Or do I have to care that we do not call > RW> l4_rt_next_period() in case of a deadline miss? > > If your thread misses its deadline right before it wanted to > call l4_rt_next_period, then l4_rt_next_period blocks the > thread until the end of the new period started due to the > deadline miss. Since this is likely not what the thread > intended to do, it's the preempter's job to handle that > situation, e.g. by ex_regs'ing the thread out of it's > l4_rt_next_period call. > OK, clear. Thanks, Rene

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freebsd style task heap memory
by Bert van Leeuwen 15 Aug '05

15 Aug '05

I've been trying to find info on this in the fiasco docs, but no luck so far. Perhaps someone on this list can give me a brief rundown. How is the heap memory for a freebsd_env style task allocated? I'm not sure whether it comes from dm_phys, rmgr, sigma0 etc. Actually, it would be nice if you could point me to a doc or info about how exactly sigma0,rmgr,dm_phys etc. interact wrt memory management. Thanks in advance!

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What happens on timeslice overrun?
by Rene Wittmann 14 Aug '05

14 Aug '05

Hi, I have 2 questions on the RT part in DROPS: 1.) I have 2 RT working threads, each with 3 timeslices: Thread 1: period=10ms ts1=30ms prio1=50 ts2=10ms prio2=30 ts3=20ms prio3=50 Thread 2: period=10ms ts1=20ms prio1=40 ts2=5ms prio2=30 ts3=10ms prio3=40 Assume both threads are ready at the same time. So thread 1 starts and does its work until it releases the voluntarily or it's preempted by its preempter-thread. So say it releases voluntarily after 20ms. Who will get the left 10ms? I guess nobody. Or can I assign my left time to a specific thread, say ts2 of thread 1, that is has 20ms after recognizing that ts1 was finished 10ms earlier?I could do with l4_rt_change_timeslice(), but this would probably not work for the the current period! (or yes?) I could even imagine that it would work in my case described above, as thread 2 would be next after ts1 of thread 1, but consider thread 2 didn't exist... 2.) Consider we have a deadline miss. And we say l4_rt_next_period(): would it wait for the beginning of the next (which means: period 1: deadline miss period 2: call next period (because we think we're still in period 1)+ wait to end of period period 3: normal work) Or do I have to care that we do not call l4_rt_next_period() in case of a deadline miss? BTW: I compiled the fiasco-kernel with apic+one shot mode. But this should not be relevant for my question. Regards, Rene

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Re: Logging/printf's in RT env
by Rene Wittmann 10 Aug '05

10 Aug '05

Hi, first of all: sorry for my late answer, I've been away... On Thu, Aug 04, 2005 at 03:09:12PM +0200, Adam Lackorzynski wrote: > On Thu Aug 04, 2005 at 13:45:12 +0200, Rene Wittmann wrote: > > I have also the problem that I want to output some of my symbols+values > > during the execution of my application. > > Furthermore I'm working in the RT scheduling mode (with APIC one shot > > mode). > > > > I have three timeslices: > > 1. mandatory > > 2. optional > > 3. "mandatory" (if part of optional was executed) > > > > The preempter recognizes timeslice overruns and sets a > > global variable, the working thread checks this variable and therefore > > knows about those "events". > > > > This works fine if my priorites are set to 50,30,50, > > but fails after a few periods with a pagefault if setting the priorities to > > 200,190,200. > > > > In each part I use some calls to LOG() to output a few things I'm > > interested in. If I leave out those LOG()-calls, it works also with the > > high priorites (200,190,200). > > So I assume, there's a LOG-buffer overflow (as the LOG priority is not > > that high)? > > > > Could I prevent this by using printf instead of LOG or is LOG just a > > kind of macro for printf? > > printf is usually also a log function. > > The priorities of the logserver are at 32, so in the first example > they're inbetween and in the latter one completely below. > > Does the PF go away when you add --prio 210 (or similar) as an argument > to log? > Yes, it goes away. But I thought that, if you have a real-time application running it will not be influenced by some "time-sharing" application as the logserver should be. > Can you send me a backtrace with unstripped binaries when the PF > happens? Thanks. > Sure, I can if you tell me how to do it... The exact error message is: app| L4RM: [PF] write at 0x01306f58, eip 0380e48b, src 9.02 app| [9.0] l4rm/lib/src/pagefault.c:78:__unknown_pf(): app| unhandled page fault And then it enters the kernel debugger. I've compiled my program with "CFLAGS = -g" so it should be unstripped, right? But when typing "bt<CR>" in the kernel debugger, there are no symbols and the output just looks like this #4 f000763b #5 f0027332 #6 f000e718 #7 f000627a #8 f000e1fd #9 f000627a #10 f000e1fd #11 f000acb0 #12 f0005f6d #13 f000627a #14 f0006280 #15 f0005c3f #16 f000627a #17 f0006280 #18 f0005aec #19 f999c5f5 #20 f00176ed #21 f0006d54 #22 f0027300 #23 f000cfa5 #24 f0006a5a #25 f000784b #26 f00272dc So I don't expect any helpful information in there or is it? BTW: my grub config looks like this: title llv1_decode (all layers, log locally) root (hd0,2) kernel /drops/bin/x86_586/l4v2/rmgr -sigma0 modaddr 0x08000000 module /l4/kernel/fiasco/build/fiasco_apic -nokdb -nowait -serial -serial_esc module /drops/bin/x86_586/l4v2/sigma0 module /drops/bin/x86_586/l4v2/log_net -net -local -ip 131.188.36.211 -buffer 4096 module /drops/bin/x86_586/l4v2/names module /drops/bin/x86_586/l4v2/dm_phys module /drops/bin/x86_586/l4v2/simple_ts module /drops/bin/x86_586/l4v2/app OK, this modaddr seems huge, but my data is just linked to the binary and I need this huge value... So how would one produce a useful backtrace inside fiasco? Or is there a way to use another debugger (gdb?)? Greetings, Rene

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Fiasco + L4Linux auf echter Hardware
by Marcel Selhorst 09 Aug '05

09 Aug '05

Hallo L4-Hackers, ich kämpfe nunmehr seit drei Tagen mit dem Versuch, Fiasco+L4Linux auf echter Hardware (Pentium 4, 512MB RAM) ans Laufen zu bekommen. Was sich ursprünglich als leichtes Unterfangen anbahnte, entpuppte sich hinlänglich als 'Fiasco' und ich bin mit meinem Latein am Ende :-) Folgende (hoffentlich einfache) Frage: Welche Einstellungen muss man im Fiasco-Kern treffen (mit welchen Experimental- Optionen), und welche im L4Linux, um es gemeinsam ans Laufen zu bekommen? Gibt es zu den einzelnen Optionen irgendwo detailliertere Dokumentationen außer der ein- bis zweizeiligen Onlinehilfe im "make menuconfig"? Ursprüngliche Kompilierungsschwierigkeiten ließen sich durch zwei CVS-Updates an zwei aufeinanderfolgenden Tagen beheben, aber der fiasco bleibt jedesmal beim booten von L4Linux stehen und friert ein, _bevor_ das eigentliche Linux-Fenster in Dope geöffnet wird. Im dmon steht als letzte Zeile: =====> L4Linux 2.6 starting <======= Hoffnungsvolle Grüße, Marcel Selhorst

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Some broken packages in remote-cvs
by Arthur Mielimonka 04 Aug '05

04 Aug '05

Hi, I checked out L4 and tried to compile it. There are some broken packages, which don't compile: /l4/pkg/cpu_reserve/examples/utcb-watch /l4/pkg/loader/examples/fprov-l4 /l4/pkg/dmon/server /l4/pkg/dsi_staticfs /l4/pkg/rt_mon/examples/dope_mon /l4/pkg/rt_mon/examples/l4vfs_dope_mon/ Just to inform you. Bye, Arthur

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Logging/printf's in RT env
by Rene Wittmann 04 Aug '05

04 Aug '05

Hi, I have also the problem that I want to output some of my symbols+values during the execution of my application. Furthermore I'm working in the RT scheduling mode (with APIC one shot mode). I have three timeslices: 1. mandatory 2. optional 3. "mandatory" (if part of optional was executed) The preempter recognizes timeslice overruns and sets a global variable, the working thread checks this variable and therefore knows about those "events". This works fine if my priorites are set to 50,30,50, but fails after a few periods with a pagefault if setting the priorities to 200,190,200. In each part I use some calls to LOG() to output a few things I'm interested in. If I leave out those LOG()-calls, it works also with the high priorites (200,190,200). So I assume, there's a LOG-buffer overflow (as the LOG priority is not that high)? Could I prevent this by using printf instead of LOG or is LOG just a kind of macro for printf? Regards, Rene

2 1

remote gdb stub
by Bert van Leeuwen 04 Aug '05

04 Aug '05

Is there a tutorial or guide somewhere about how to use remote gdb (from a linux machine) to debug an L4 task? I haven't been able to find much more info about this other than casual mention that it is supported...

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