l4-hackers June 2012

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

23 participants
30 discussions

porting file system for L4/fiasco & L4re
by mkmaeng 13 Jun '12

13 Jun '12

Hello everyone. I have questions about using file system for L4/fiasco & L4re. I tried to convert applications using file I/O to L4 environment but I failed. So I realized that I need to use file system in L4/fiasco, but I couldn't find any documents about it. I have two questions. 1. How can I put root file system on L4/fiasco? Are there any references or documents that I can refer? 2. How can I verify whether file system is working or not. Are there any libraries for L4 to use file I/O? I hope you to suggest direction to solve this problems for me. Thank you very much. Best regards, Minkyu Maeng.

1 0

I have a question about l4linux
by Ednilson Ricardo 11 Jun '12

11 Jun '12

Hello, I would like to know what forms of input and output data L4Linux. thank you

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porting file system for L4/fiasco & L4re
by mkmaeng 11 Jun '12

11 Jun '12

2 1

l4 linux questions
by Ryan Brown 11 Jun '12

11 Jun '12

The l4 linux page doesn't have much information about the l4re version of l4 linux. How stable is it? What is the performance like? Is there any way to mount the l4re VFS inside linux? I was thinking perhaps I could mount it using 9p to an l4 server. But it looks like 9p needs tcp/ip. Is there a way I can use something like l4shmnet to talk to an l4 server instead of talking to another l4linux?

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Hardware irq and vcpu entry
by Pierre Larus 11 Jun '12

11 Jun '12

Hi I am porting an RTOS on L4RE. The RTOS run in a l4_thread and I am currently trying to handle hardware timer irq. I would like to know if it is possible to attach an hardware irq (timer irq) to a vcpu entry ? I try to do this in a vpcu thread: vcpu_state->state = L4_VCPU_F_EXCEPTIONS | L4_VCPU_F_IRQ; vcpu_state->entry_ip = (l4_addr_t)&vcpu_entry; vcpu_state->user_task = L4_INVALID_CAP; InitClockDevice(); icucap = l4re_get_env_cap("icu"); irqcap = l4re_util_cap_alloc(); l4_factory_create_irq(l4re_global_env->factory, irqcap); l4_icu_bind(icucap, 38, irqcap); l4_irq_attach(irqcap, 0x38, current_thread_cap); StartUpMain(); But this solution does not work. The thread vcpu support works because when I use the l4_irq_trigger() function the irq are catched by the vcpu entry. The irq attach also works because I can handle hardware interrupt using a dedicated thread: icucap = l4re_get_env_cap("icu"); irqcap = l4re_util_cap_alloc(); l4_factory_create_irq(l4re_global_env->factory, irqcap); l4_icu_bind(icucap, 38, irqcap); l4_irq_attach(irqcap, 0x38, current_thread_cap); while (1) { l4_irq_receive(irqcap, L4_IPC_NEVER); isr_handler(); } Regards, Pierre LARUS

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l4linux GPU direct access
by Abhishek Gupta 07 Jun '12

07 Jun '12

Hi, I was trying to run xserver on l4linux using vesa frame buffer (l4 is running on kvm) and virtual machine hangs and it seems that a infinite loop is started which is continuously try to do something but doesn't succeed. When I tried to debug it using gdb, it displays 0xb6ee9b28 in SetResetBIOSVars (pInt=0x820f5a0, set=<value optimized out>) at ../../../../hw/xfree86/int10/helper_exec.c:686 this code is from the xserver 1.7.7 static void SetResetBIOSVars(xf86Int10InfoPtr pInt, Bool set) { int pagesize = getpagesize(); unsigned char* base = xf86MapVidMem(pInt->scrnIndex, VIDMEM_MMIO, 0, pagesize); int i; if (set) { for (i = BIOS_SCRATCH_OFF; i < BIOS_SCRATCH_END; i++) MEM_WW(pInt, i, *(base + i)); } else { for (i = BIOS_SCRATCH_OFF; i < BIOS_SCRATCH_END; i++) /*line 685*/ *(base + i) = MEM_RW(pInt, i); /*line 686*/ //This line of code is not working } xf86UnMapVidMem(pInt->scrnIndex,base,pagesize); } The value of base becomes 0 after xf86MapVidMem func is called. So my Guess is that this func is failing and returning NULL but I am not able to figure out why Also I read in previous years mailing list that Linux tries to execute int10 to set the VESA mode but L4 applications are not allowed to execute real-mode code. Does this have anything to do with my problem?? How can I fix this problem? Also, Is there a way to allow L4 applications to execute code in real mode and then switch back? May be add some code to L4 to allow applications to execute code in real mode and then switch back. Abhishek Gupta Indian School of Mines

2 1

Fiasco.OC: sigma0 stucks in ipc-path
by Stefan kalkowski 07 Jun '12

07 Jun '12

Dear kernel-hackers, I think I came along a problem in the IPC-path of Fiasco.OC sometimes in the past, but it was somehow hard to reproduce. But now I've an example that quite reliable triggers the issue. The symptom in the past, and in the concrete example was that our roottask in Genode (called core) was requesting memory from sigma0, either implicitly just by touching some memory-area, like a ROM-module loaded by the bootloader, or explicitly by using the sigma0-protocol, e.g. to request I/O memory for the framebuffer. After that the request was received by sigma0, and also processed, but the answer never reached the faulter/client in this case the core-pager thread. The typical picture in the kernel-debugger then looks like the following: http://pastebin.com/cFvn1NV2 sigma0 is marked as ready, but it still stucks in the ipc-syscall. By instrumenting the kernel I could break down the point where sigma0 never returns. It is when trying to establishing the actual mapping in 'Thread::transfer_msg_items' in file src/kern/thread-ipc.cc. The spot is the following: ``` cpu_lock.clear(); L4_error err = fpage_map(snd->space(), sfp, rcv->space(), L4_fpage(buf->d), item->b, &rl); cpu_lock.lock(); ``` After the cpu lock is given away, sigma0 never aquires it back successfully. It looks to me like a race-condition, nevertheless simply letting the lock being locked doesn't solved the problem ;-). Maybe given your insight knowledge, you're much faster in tracking the problem down to its root? I've to add, that the problem occurred on x86 as well as ARM, on different QEMU versions, as well as real hardware. I also could reproduce it with slightly older versions of Fiasco.OC, and in different development stages of Genode. Nevertheless, it was never that reliable to reproduce. The current example which reproduces it reliable at least with my QEMU (qemu-kvm-0.14.0) version. You can find in form of an ISO-image here: http://dl.dropbox.com/u/82567292/avplay.iso You can try the iso-image like the following: qemu -no-kvm -m 256 -soundhw all -serial mon:stdio -cdrom avplay.iso Or, if you've to build it on your own, here is my topic branch, including the avplay run-script that triggers the problem: https://github.com/skalk/genode/tree/fiasco.oc-ipc-issue To compile and run it yourself you've to do the following steps (after installing the genode toolchain from http://genode.org/download/tool-chain): git clone git@github.com:skalk/genode.git cd genode git checkout -b issue origin/fiasco.oc-ipc-issue git clone git@github.com:genodelabs/linux_drivers.git make -C base-foc prepare make -C libports prepare PKG="libav libc sdl zlib" tool/create_builddir foc_x86_32 BUILD_DIR=build sed -i "/#REPOSITORIES.*libports/s/#//" build/etc/build.conf sed -i "/#REPOSITORIES.*linux_drivers/s/#//" build/etc/build.conf make -C build run/avplay Thank you in advance & best regards! Stefan

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[l4ankh] Problems with fixed l4ankh
by Timur 03 Jun '12

03 Jun '12

Hi! I had fixed the l4ankh driver and after that it started to work properly. Now only thread is used to receive packets. In lines 158-162 we clear the rcv buffer: that is necessary to be done as after opening a session we start to receive packets that should not be served; otherwise the response time will be quite slow. This is not the best solution, but I do not have time to make it better. Now I face the following problem: the driver in ankh (I use 8139cp) stops receiving packets after some time (for me it is usually 3-4 minutes). This situation occurs when the interrupt handler was called and the device register IntrStatus already equals "zero". An interrupt doesn't work after that. -- Galiullin Timur

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I have a question about L4Linux
by Ednilson Ricardo 03 Jun '12

03 Jun '12

Hello, I have some doubts about the L4Linux, can you help me? *** What are the purposes of L4Linux?Hardware subjaecnte that OS (capacity and types of memory, processor, bus, etc.).*** With this operating system can work? What capacity and type of hardware it runs? What is the architecture that it needs to function? the type of memory itworks? processors that it works, buses, and everything involved in the operating system. What it needs hardware to run? What type of application it serves?Interaticas, batch, real-time, etc..*** What are the characteristics related to the accomplishment of the application,low response time, low turnaround time, etc.. (View aqielas applications, which it meets the requirements) as it meets these requirements? -> It is otimisado,blibioterca specific uses, he uses some dynamic code that allows it meets these requirements, then how it will work.*** What is your architecture? (Monolithic? Layered? Micro-kernel virtual machineor some other system) PREFERENCE TO EXPLAIN AND THE GREATERLEVEL POSSIBLE to detail.*** If the operating system is not supposed or threads (the core of User, hybrid?)And how the theads are implemented in the OS (if it meets it has a mechanism forimplementation (How it was implemented)

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Debugging l4linux + l4re
by Haohui Mai 03 Jun '12

03 Jun '12

Hi folks, I'm running mag + L4Linux on a real machine that doesn't have a serial port. It's really difficult to debug -- I'm wondering if there're any ways to open a new window under mag, and to redirect all serial port I/O to that window? It would be really helpful for debugging. I appreciate if anyone could share if he happens wrote this program before, or giving me some suggestions. Your help is appreciated! ~Haohui

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l4-hackers June 2012