March 2017 - l4-hackers - example.com Site

Porting Fiasco + L4Re to Raspberry Pi 2
by Antoine DEBUT 26 Nov '17

26 Nov '17

Hello l4-hackers, I am currently working on porting the Fiasco.OC micro kernel onto the Raspberry pi 2. Therefore, I am struggling with memory mapping, and I encounter the following error when launching the default 'hello' entry: L4 Bootstrapper Build: #2 Tue Feb 23 11:57:19 CET 2016, 4.8.3 20140303 (prerelease) Scanning up to 1024 MB RAM, starting at offset 32MB Memory size is 1024MB (00000000 - 3fffffff) RAM: 0000000000000000 - 000000003fffffff: 1048576kB Total RAM: 1024MB Scanning fiasco Scanning sigma0 Scanning moe Moving up to 5 modules behind 1100000 moving module 02 { 10db000-110c4d7 } -> { 11cc000-11fd4d7 } [201944] moving module 01 { 10c9000-10da373 } -> { 11ba000-11cb373 } [70516] moving module 00 { 1043000-10c889f } -> { 1134000-11b989f } [546976] moving module 04 { 1029000-10425af } -> { 111a000-11335af } [103856] moving module 03 { 100f000-102849b } -> { 1100000-111949b } [103580] Loading fiasco Loading sigma0 Loading moe find kernel info page... found kernel info page at 0x2000 Regions of list 'regions' [ 1000, 1aff] { b00} Kern fiasco [ 2000, 92fff] { 91000} Kern fiasco [ 93000, 930eb] { ec} Root mbi_rt [ c0000, c9c33] { 9c34} Sigma0 sigma0 [ d0000, d6177] { 6178} Sigma0 sigma0 [ 140000, 16905b] { 2905c} Root moe [ 170000, 17b58b] { b58c} Root moe [ 1000000, 100e4ff] { e500} Boot bootstrap [ 1100000, 1133fff] { 34000} Root Module API Version: (87) experimental Sigma0 config ip:000c0100 sp:00000000 Roottask config ip:00140250 sp:00000000 Starting kernel fiasco at 000012b8 Non-HYP kernel detected but running in HYP mode, switching back. Hello from Startup::stage2 Assertion failed at /home/adebut/Documents/snapshotTest/l4re-snapshot-2015123115/src/kernel/fiasco/src/kern/buddy_alloc.cpp:101: (unsigned long)block >= _base Press any key to reboot. I am currently working on the latest snapshot (2015123115), with U-Boot as a bootloader, and testing on a real board (Raspberry Pi 2 model B V1.1). The entry built is the standard 'hello', and I use the ramdisk-arm.rd given in the snapshot. I did add a custom Bsp for the board, mainly based on the first Raspberry Pi except for the Base Address, that is 0x3F000000 instead of the first Pi's 0x20000000. I highly think that it is an address configuration problem, because it first happened when I did expand the RAM size to 1024MB. With further investigation, I found out that it was the kernel memory allocation that causes this error, and suspect an incorrect MMU mapping. This suspicion comes from the fact that the assertion takes the address _base (0xf0400000) and the currently allocated block (0xee100000). I did not modify any parameter in the kern/arm/mem_layout-arm.cpp file on the Fiasco directory, which provides the default ARM addressing. Maybe that's where my error comes from ? How can I correctly configure my memory mapping, besides what I already configure in the Bsp (given in attachment) ? Also, it is the first time that I am assigned for porting a system, do you have some hints, like important steps to follow ? I am pretty sure it is a newbie error, but I cannot figure it out for now :( Thanks in advance for your time, -- Antoine Debut EPITA 2016 - GISTRE

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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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Benchmarks in l4
by Maxim Baryshnikov 01 Jun '17

01 Jun '17

Hello everybody, Does the L4re contain some kind of simple performance benchmarks which are already prepared to use? I've tried to launch some demos from the ferret package but not succeed... Thank you in advance for any suggestions. Sincerely, Maxim Baryshnikov.

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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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Trying to build L4 on NixOS
by Mateusz Czaplinski 09 Apr '17

09 Apr '17

I'm trying to build L4 on NixOS in a VM (long term goal: try to learn how to replace NixOS's kernel with L4Linux, then maybe Genode). I'm getting an error like below: undefined reference to `__stack_chk_fail' during linking of bootstrap.elf - in a GCC's error-barf just after: [bootstrap] ==> Linking bootstrap.elf I've put up the precise Nix expression/script I'm using to build it on github - at: https://github.com/akavel/l4.nix/blob/0108dfcf8d84780e1ba884c41ece0d2dbf4dd… but what it generally boils down to is a sequence of commands like this: $ wget http://os.inf.tu-dresden.de/download/snapshots/l4re-core-2016082114.tar.xz $ tar xf l4re-core-2016082114.tar.xz $ cd l4re-core-2016082114 $ mkdir out $ cp src/l4/mk/defconfig/config.amd64 out/l4/.kconfig $ make -C src/l4 O=out/l4 olddefconfig $ make -C out/l4 I've tried various additional changes, based on some snippets found here and there on teh Internets, like: - adding V=0 to the last make (no idea what it does yet, just some cargo culting) - adding NIX_CFLAGS_COMPILE = "-fno-stack-protector"; to the Nix expression/script (also not really sure where it applies in the stack); but none of the above helped. Any idea what I could try doing to push it further? Thanks, /Mateusz.

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Questions about Fiasco.OC scheduler and L4Linux
by Marc CHALAND 02 Apr '17

02 Apr '17

Hi, I'm doing a study to port old software on top of Fiasco.OC. This soft uses routines which blocks thread scheduling between EnterRegion and LeaveRegion call. Is there any equivalent on TUDOS ? Did somebody already get this challenge ? I would like to know if L4Linux uses Fiasco.OC scheduler or a user land one ? For our i.MX7d board, Freescale provides Linux drivers on 4.1. I don't know yet how many drivers we will need. Do you think it is better to port drivers from 4.1 to L4Linux 4.3 or later or get a L4Linux 4.1. I have no idea about the complexity on doing this. Regards Marc

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L4linux __raw_writesl/readl undefined
by Manolis Ragkousis 01 Apr '17

01 Apr '17

Hello everyone, I am trying to enable sd card support on my zedboard running l4linux and I get this error: ERROR: "__raw_writesl" [drivers/mmc/host/mmci.ko] undefined! ERROR: "__raw_readsl" [drivers/mmc/host/mmci.ko] undefined! make[2]: *** [../scripts/Makefile.modpost:91: __modpost] Error 1 make[1]: *** [/home/manolis/repos/l4linux/Makefile:1173: modules] Error 2 make[1]: *** Waiting for unfinished jobs.... LD ldrImage GZIP vmlinuz LOCINST vmlinuz make[1]: Leaving directory '/home/manolis/repos/l4linux/build' make: *** [Makefile:150: sub-make] Error 2 In order to enable sd card support I understand that I need to enable MMC/SD/SDIO card support in the kernel + ARM AMBA Multimedia Card Interface support. I have followed the instructions from previous emails in this list [1][2]. What am I missing? Is there a config option which enables raw writes/reads on top of L4? Thank you for you time and help, Manolis [1] https://os.inf.tu-dresden.de/pipermail/l4-hackers/2014/006296.html [2] https://os.inf.tu-dresden.de/pipermail/l4-hackers/2014/006417.html

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Can't find device node in /dev/ directory!
by li94575 21 Mar '17

21 Mar '17

Hi, I added some drivers in l4linux, of course, I assigned the corresponding peripheral resources (iomem, irq) to these drivers. From the driver's output log, it seems that they all work well, but when entering the command line, I could not find any relevant device node in /dev/ directory. To my confusion, I can see these devices info in /sys/ directory. The command line args is showing below: mem=64M console=ttyLv0 l4x_rd=rom/ramdisk-" .. L4.Info.arch() .. ".rd ramdisk_size=4000 Any idea?

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Re: Extending l4sys by reading/writing register values of a preempted thread
by Christian Ludwig 21 Mar '17

21 Mar '17

Hi, > I want to implement a new syscall for getting/setting stored register > values of a specific thread (identified by its cap). Why not use ex_regs() on the thread to trigger an exception. That way, the attached userland exception handler can introspect the thread's complete register set. It can also alter the registers, so that the thread continues to run with the modified register set. Is there anything more you need? > Before implementing the syscall, I need to better understand the > kernel-part of Fiasco.OC. Can you help me answer the following questions > and point me to the source code regarding each question: > > * Where (in the source code) are threads preempted and their register > state stored? A thread's userland registers are stored on every entry to the kernel. The class in Fiasco is called Entry_frame. The userland exception handler mentioned above modifies that Entry_frame. > * Where is the register state of a thread loaded to the CPU and the > thread started (e.g. after a preempt)? When the scheduler selects a thread, its userland state (Entry_frame) is restored on exit from kernel mode. > * How can I introspect the stored thread register of a thread in the > kernel debugger JDB? > ** My thoughts: Is it K<kobj_ptr> with kobj_ptr of the thread and the 3 > lines beginning with PC=...? > e.g. > " > PC=010579cc USP=200ffdb0 smlatbeq r9, r0, r2, r5 > [0] 00000003 000010c0 00218003 00000000 tsteq000r5, ip, rrx > [8] 200ffdb0 200ffe40 01086ef0 200ffe98 [c] 200ffef8 010579cc fffffff8 > 20000010 > " Yes, that PC line is the userland program counter. the USP is the userland stack pointer. All userland registers are located at the top of kernel stack for a particular thread. > I also have another, short, off-topic question: > * How can I introspect the capability space of a task inside the kernel > debugger? In short mode, press 's' for a list of all tasks. Select the task in question and the press 'o' to see the capability space for that task. Hope that helps, - Christian

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Extending l4sys by reading/writing register values of a preempted thread
by Denis Huber 13 Mar '17

13 Mar '17

Dear L4 hackers community, I want to implement a new syscall for getting/setting stored register values of a specific thread (identified by its cap). Preliminary note: I'm using the ARM architecture. Before implementing the syscall, I need to better understand the kernel-part of Fiasco.OC. Can you help me answer the following questions and point me to the source code regarding each question: * Where (in the source code) are threads preempted and their register state stored? * Where is the register state of a thread loaded to the CPU and the thread started (e.g. after a preempt)? * Where is the register state stored of each thread? * How can I introspect the stored thread register of a thread in the kernel debugger JDB? ** My thoughts: Is it K<kobj_ptr> with kobj_ptr of the thread and the 3 lines beginning with PC=...? e.g. " PC=010579cc USP=200ffdb0 smlatbeq r9, r0, r2, r5 [0] 00000003 000010c0 00218003 00000000 tsteq000r5, ip, rrx [8] 200ffdb0 200ffe40 01086ef0 200ffe98 [c] 200ffef8 010579cc fffffff8 20000010 " I also have another, short, off-topic question: * How can I introspect the capability space of a task inside the kernel debugger? Kind regards, Denis

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