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real time application example in l4re
by cem akpolat 01 Jul '14

01 Jul '14

Dear all, is there any example for a real-time applications running on l4re? I see in the slides prepared by TU Dresden that there is always a separation between realtime and non-realtime, but I couldn't find any example for that. If there is an example, could you refer it? Cheers, Cem Akpolat

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IO configuration language
by Martin Schröder 25 Jun '14

25 Jun '14

IO supports two configuration formats. The (legacy format ?) "IO configuration language" and a (newer ?) lua based one. Except for some examples and the syntax file ioconfig.vim I could not find much documentation. But anyway I am running into trouble when using the lua based one instead of my existing (so far working) old one. I have something like this (two network cards with each dmamem): === (old one) hw-root { NIC0 => new Device() { .hid = "foodevice"; new-res Mmio(0x111 ... 0x222); } NIC1 => new Device() { .hid = "foodevice"; new-res Mmio(0x333 ... 0x444); } DMAMEM0 => new Device() { .hid = "dmamem"; new-res Mmio_ram(0x80000, 0); } DMAMEM1 => new Device() { .hid = "dmamem"; new-res Mmio_ram(0x80000, 0); } } client0 => new System_bus() { "foo.dev0" => wrap(hw-root.NIC0); "dmamem" => wrap(hw-root.DMAMEM0); } client1 => new System_bus() { "foo.dev1" => wrap(hw-root.NIC1); "dmamem" => wrap(hw-root.DMAMEM1); } === and want to convert it into something like this: === (new one) Io.hw_add_devices { NIC0 = Io.Hw.Device { hid = "foodevice" Io.Res.mmio(0x111, 0x222) }, NIC1 = Io.Hw.Device { hid = "foodevice" Io.Res.mmio(0x333, 0x444) }, DMAMEM0 = Io.Hw.Device { hid = "dmamem"; Io.Mmio_data_space(0x80000, 0x80000); }, DMAMEM1 = Io.Hw.Device { hid = "dmamem"; Io.Mmio_data_space(0x80000, 0x80000); } } local hw = Io.Hw Io.add_vbusses { client0 = Io.Vi.System_bus(function () dev0 = wrap(hw:match(NIC0)); dev1 = wrap(hw:match(DMAMEM0)); end), client1 = Io.Vi.System_bus(function () dev0 = wrap(hw:match(NIC1)); dev1 = wrap(hw:match(DMAMEM1)); end) } === So dev0 = wrap(hw:match(NIC0)); seems to be wrong. In all the examples I fould the hid-string dev0 = wrap(hw:match("foodevice")) is always used. So three questions: 1) How can I use the device in the example if the hid is not unique? I even tried wrap(hw:device(NIC0)) but this does not work eiher. 2) How can I set the device name for client0/client1 into "foo.dev0" for dev0 as in the (old) example above? dev0.set_name("foo.dev0"); seems not to be the right one. 3) Is Io.mio_data_space(0x80000, 0x80000) the right replacement for "new-res Mmio_ram(0x80000, 0);" ? Best regards, Martin

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A conceptual question about IPC
by Jorge Ventura 24 Jun '14

24 Jun '14

I have been reading several papers about micro kernel and they explain how critical the IPC design is for kernel performance, most of them point to use of register, incomplete context switch and so on. Here is my question: Is not possible to use the MMU and just execute a page swap between address spaces ? Make changes in the page table is not something fast ?

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Setting task priority in loader configuration script
by Peter Howard 24 Jun '14

24 Jun '14

Dear all, I've looked through the documentation, but it doesn't seem clear how you set the priority of a task as you create it from a .cfg script. I've tried: loader:start({caps = { ... }, l4re_dbg = L4.Dbg.Warn, log = {"foo", "red" }, priority = 100}, "rom/foo"); But I'm not seeing any difference from that, with priority < 0x10, > 0x10, or unset. (I got the 0x10 value from http://os.inf.tu-dresden.de/l4env/doc/html/loader/p_script.html) So, is that the correct way? If now, what is the correct way to specify priority? Thanks, -- Peter Howard <pjh(a)northern-ridge.com.au>

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Fwd: l4shmnet and its structure
by cem akpolat 22 Jun '14

22 Jun '14

Hi, "So I understand that you configured one L4Linux with two l4shmnet network interfaces and one of those two did not work? Hard to tell for me what's wrong without more info." I added printf lines to shmc.c file and the output I get the following output while a connection is created btw. the server and the first client. //*************************************// client1 | l4shmc_create : starting client1 | l4shmc_create : l4re_ns_register_obj_srv returned error client1 | l4shmc_attach_to : starting client1 | l4shmc_attach_to : no problem, returning L4_OK client1 | l4shmc_add_chunk : starting client1 | l4shmc_add_chunk : executing chunk_get client1 | l4shmc_add_chunk : in the else side due to offs client1 | l4shmc_add_chunk : returning L4_OK client1 | l4shmc_add_signal : starting client1 | l4shmc_add_signal : returning L4_EOK client1 | l4shmc_get_chunk_to :starting server | l4shmc_get_chunk_to :starting net shm0: shm0: L4ShmNet established, with 54:42:00:00:ff:01, IRQ 66 client1 net shm0: shm0: L4ShmNet established, with 54:42:00:00:ff:02, IRQ 65 And the following output between the server and the second client: //*************************************// client2 | l4shmc_create : starting client2 | l4shmc_create : l4re_ns_register_obj_srv returned error client2 | l4shmc_attach_to : starting client2 | l4shmc_attach_to : no problem, returning L4_OK client2 | l4shmc_add_chunk : starting client2 | l4shmc_add_chunk : executing chunk_get client2 | l4shmc_add_chunk : in the else side due to offs client2 | l4shmc_add_chunk : returning L4_OK client2 | l4shmc_add_signal : starting client2 | l4shmc_add_signal : returning L4_EOK client2 | l4shmc_get_chunk_to :starting server | l4shmc_get_chunk_to :starting net shm1: shm1: L4ShmNet established, with 54:42:00:00:ff:04, IRQ 67 //*************************************// As you can see, the second client does not respond after the connection established message from the server. I have two questions regarding this problem: 1) Is the message "l4re_ns_register_obj_srv returned error" the source of the problem? If so, then what might be the reason for this error? And also, why does the connection work properly between the first server and the client if that is the source of the problem? 2) Could it be the case that the second client obtains the same IRQ number with the first client(IRQ 65) or the server (IRQ66 or 67), and therefore the trigger signal is not received by the second client? How can I detect this problem? Which function is responsible for the IRQ numbering? As you can see, the second client does not respond after the connection established message from the server. I have two questions regarding this problem: 1) Is the message "l4re_ns_register_obj_srv returned error" the source of the problem? If so, then what might be the reason for this error? And also, why does the connection work properly between the first server and the client if that is the source of the problem? 2) Could it be the case that the second client obtains the same IRQ number with the first client(IRQ 65) or the server (IRQ66 or 67), and therefore the trigger signal is not received by the second client? How can I detect this problem? Which function is responsible for the IRQ numbering? Thank you very much for your time, Cem

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RCU period
by Yuxin Ren 22 Jun '14

22 Jun '14

Hi I do not understand the period in Rcu class. How do we use it? Now it is 10ms, how is it calculated? Thanks a lot.

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How does Fiasco implement printf
by Yuxin Ren 22 Jun '14

22 Jun '14

Hi, I think printf usually invoke system call. But in Fiasco only one system call is capability invocation. So what capability is invoked by printf? Or Fiasco implements printf in user level, so printf triggers a normal IPC? Thank you. Best

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Question about seL4 on July 29th
by Jorge Ventura 21 Jun '14

21 Jun '14

Anybody knows what kind of Open Source License is expected to be deployed with seL4 on July 29th ?

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Istream beginner help
by ba_f 17 Jun '14

17 Jun '14

Hallo Hackers, for design reason i would like to use separate Istream & Ostream instead of IOstream with call(). ostream.send() does work, but i cant manage istream.receive(). It keeps waiting for ever. I did edit the client from pkg/examples/clntsrv, the server sends the result, so there should be something to receive. What am i missing? // pkg/examples/clntsrv/myClient.cc static L4::Cap<void> server; static int func_neg_transmit() { L4::Ipc::Ostream oStream(l4_utcb()); l4_uint32_t val = 8; s << l4_umword_t(Opcode::func_neg) << val; int r = l4_error(s.send(server.cap(), Protocol::Calc)); } static int getResult() { L4::Ipc::Istream iStream(l4_utcb()); l4_uint32_t val; // while ( iStream.has_more<l4_uint32_t>()) { // doesnt work neither int r = l4_error(iStream.receive(server.cap())); printf("receive success\n"); // doesnt pass here iStream >> val; } int main() { server = L4Re::Env::env()->get_cap<void>("calc_server"); func_neg_transmit(); getResult(); return 0; } THANK YOU

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Multiple IPC_Gate channels per task
by professor xavier 13 Jun '14

13 Jun '14

Hi, I am a newbie to L4 and have a simple question about the IPC_Gate feature. Can a single task support multiple IPC_Gates? If so, can you please provide an example of a *.cfg script that shows this? Thank you. px

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