l4-hackers October 2014

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

21 participants
22 discussions

Graphical desktop, l4con, mag
by teclis High Elf 02 Jun '17

02 Jun '17

Guten Tag, I've got the Hello app runing with fiasco and l4re in qemu, how do I get the graphical UI and console running that I see on the screen shots page? Do I need to use l4con and mag? I don't see an entry with l4con in modules.list. danke * <http://german.about.com/library/media/Audio/gutentag.wav>*

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libfs/ FUSE on L4Re
by Stark, Josef 31 May '17

31 May '17

Hello, yesterday I came across a very interesting paper titled "Porting FUSE to L4Re", accessible here: http://os.inf.tu-dresden.de/papers_ps/pester-beleg.pdf For porting FUSE, the author uses a library called "libfs" which provides filesystem request forwarding and processing, if I understood correctly. It reads as if libfs is already included in L4Re. However, I couldn't find neither FUSE nor libfs in the current L4Re snapshot. Are they by any chance publicly available somewhere else, or are both not to be published? Cheers, Josef

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shared dataspace for l4re_kernel/ registering additional caps in ned
by Stark, Josef 12 Mar '15

12 Mar '15

Hello all, for a project, I want to be able to load (elf-)binaries not only from the filesystem, but also from the network (receive binary, then start it.) For this, I will write a L4 app (let's call it "manager" for now) which handles the network part and then tells ned to start the received binary via a special "filename". I already modified ned so that its LUA-interface is exposed to other apps via a capability. But here comes the first problem: Normally you specify the capability table of a task and an IPC channel in the lua-config file, which ned reads. Ned then prepares the channel and the caps table and starts the task, which then can register the capability. Otherwise, registering fails (the example would do a printf("Could not register my service, is there a 'calc_server' in the caps table?\n");) So... how do I specify which capabilities ned itself can have/register? Currently, I need to have a lua-config which tells ned to start another instance of ned with the required permission to register the capability. But is there any way to avoid having two ned instances and making the first (and only) instance able to register the cap? Second problem: I found out, that ned (also moe) doesn't start the desired app directly but instead starts the l4re binary (source located in src/l4/pkg/l4re_kernel), passing it the filename of the desired binary. l4re, once started, gets the dataspace of this file and then ultimately starts the app. For my purpose, I would modify l4re_kernel so that if it detects the special "filename" mentioned above, it does not read the file from the filesystem but loads the binary that the "manager" received over the network. To get the data from the manager to the l4re_kernel instance, I thought that a shared dataspace or a shared memory area l4shmc_area_t like in prdocons.c example would be suitable. However, again, both of these things normally require special parameters in the lua config file (as can be seen in the examples), but I have no clue how to do this to l4re_kernel since it is not loaded from such a file, but loaded implicitly each time a new task is started. (so I guess this makes it even harder than the problem with ned since ned is only started once.) Does anyone have ideas on how to solve these? If someone finds that I phrased this too opaque, please let me know. Best regards, Josef Stark

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is there a way to run the compiled arm on Nexus S ?
by cem akpolat 04 Nov '14

04 Nov '14

Dear all, I have compiled couple of days ago l4android for arm architecture, and now I want to boot it on Nexus S, however, I couldn't find a way to tun bootstrapLinuxAndroid.elf file on arm based architecture. I have already seen in some research papers (one of them is as follows). http://www.isti.tu-berlin.de/fileadmin/fg214/liebergeld/spsm03-lange.pdf How could be l4android booted on the Nexus S? Thanks, Best Regards, Cem Akpolat

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Dummy irq
by teclis High Elf 01 Nov '14

01 Nov '14

If I wanted to create a dummy irq that didn't actually exist in hardware but I could use for asynchronous notification between processes or between a hypervisor and a VM how would I do that in L4Re? What would the dummy entry look like in the .devs file? thanks

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Microkernel Stammtisch Dresden: Nov 6, Shamrock
by Julian Stecklina 29 Oct '14

29 Oct '14

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Hello fellow microkernel hackers, for everyone outside the Dresden, Germany area this mail is unfortunately off-topic. For everyone else there is going to be another Microkernel Stammtisch on Thursday, November 6th in the Shamrock Irish Pub[1]. If you intend to join, please leave a note using the link below, so I can reserve a table: https://dudle.inf.tu-dresden.de/ukvly-beer/ See you there, Julian [1] Kleine Brüdergasse 1, Dresden -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iEYEARECAAYFAlRQL34ACgkQ2EtjUdW3H9l5qwCdHVLdLwthN4i5n8p7pQrqmr46 JzgAn18ML6+KoyLQZGEwg3jQW9CzOmUv =wapd -----END PGP SIGNATURE-----

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memcpy(): alignment error
by ba_f 25 Oct '14

25 Oct '14

Hello L4-Hackers, i get an "alignment error" when trying to memcpy(). The error occurs in a raw L4-Task (how do u "officially" name that?), no L4Linux. However, the error comes with the following line: memcpy(0x80006e80, 0x80006e84, 4); And this is the message: KERNEL0: alignment error at 80006ece (PC: 00079be8, SP: 80006b08, FSR: 410801, PSR: 60000010) No signal handler found Any idea? Thanks, again. PS: I don't know if the Fiasco Debugger would help for this problem, but i didn't have time to learn working with it, yet. Sorry for that.

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exec()
by teclis High Elf 23 Oct '14

23 Oct '14

Could some one please point me to or give me example code to do the L4Re equivalent of UNIX exec(), spawn a new process? thanks

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dynamic loading
by teclis High Elf 21 Oct '14

21 Oct '14

Does L4Re support dynamic loading? Is there an elf loader or shell? If so how do I do it? I want to run directly with L4Re. No l4linux. thanks

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SMP for L4Linux on i.MX6
by Uwe Geuder 19 Oct '14

19 Oct '14

Hi! We have an i.MX6 quadcore SoC and obviously we would like to use more than 1 core in L4Linux. So far I have not succeeded to do that. jdb shows 4 CPUs and some tasks on different ones, so I assume our Fiasco configuration supports SMP. Still all L4Linux tasks are on the same one and CPU stress testing shows clearly that only 1 CPU is in use. >From an earlier posting on this list I found the L4.Proto.Scheduler configuration for ned. I tried various options but there was no effect, L4Linux user space runs on 1 core only. -- CPUs 1 + 2 -- scheduler = L4.Env.user_factory:create(L4.Proto.Scheduler, 0x18, 0x8, 6), -- maybe no mask means all CPUs? scheduler = L4.Env.user_factory:create(L4.Proto.Scheduler, 0x18, 0x8), Next I looked at our L4Linux configuration and indeed CONFIG_SMP was not set. However after enabling it the kernel does no longer build: arch/arm/mach-imx/built-in.o: In function `imx_smp_prepare': /home/geuder/projects/c4c/l4-bundle/l4linux/arch/arm/mach-imx/platsmp.c:79: undefined reference to `scu_enable' /home/geuder/projects/c4c/l4-bundle/l4linux/arch/arm/mach-imx/platsmp.c:79: undefined reference to `scu_enable' arch/arm/mach-imx/built-in.o: In function `imx_smp_init_cpus': /home/geuder/projects/c4c/l4-bundle/l4linux/arch/arm/mach-imx/platsmp.c:71: undefined reference to `scu_get_core_count' arch/arm/mach-imx/built-in.o: In function `v7_secondary_startup': /home/geuder/projects/c4c/l4-bundle/l4linux/arch/arm/mach-imx/headsmp.S:33: undefined reference to `v7_invalidate_l1' /home/geuder/projects/c4c/l4-bundle/l4linux/arch/arm/mach-imx/headsmp.S:35: undefined reference to `secondary_startup' The SCU http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.ddi0407e/CDDEHD… has to do with cache coherency, obviously important on SMP. The SCU code is in native ARM, but not in L4 ARM. I somehow have the feeling just copying it is not enough. Does the virtual CPU seen by L4Linux need to control/use the SCU or is that something made completely transparent by the virtual cpu offered by L4? v7_secondary_startup code is behind !defined(CONFIG_L4). The code does a lot of MMU initializion stuff, so my guess is this cannot worked unchanged under L4. So the question is: Is SMP for i.MX6 unimplemented or at least untested or am I doing something completely wrong here? Somebody here mentioned VCPU. I have not studied that concept yet. We have CONFIG_L4_VCPU=y Regards, Uwe Geuder Nomovok Ltd. Tampere, Finland uwe.gxuder(a)nomovok.com (bot test: humans correct 1 obvious spelling error)

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l4-hackers October 2014