l4-hackers October 2014

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

21 participants
22 discussions

Teaching OS Course notes
by teclis High Elf 17 Oct '14

17 Oct '14

Hi, I understand that Fiasco/L4Re is used as the teaching operating system at TU Dresden. Are there any course notes or lab notes available for courses at TU Dresden that used and/or covered Fiasco/L4Re? All the lab tutorials and course notes pertaining to the teaching operating systems used at MIT and Stanford are available online but I couldn't find anything similar for Fiasco. thanks

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raw L4Task: Flash Access & Variable
by ba_f 16 Oct '14

16 Oct '14

Hello and thank u so far, >> Adam wrote: > It is possible. But of course there needs to be a driver for your flash > and a filesystem (if needed). And there's none. > There's a tmpfs, i.e. a filesystem that can store files, however, not > across reboots. Maybe that helps you already? Yes, volatile storage would do the trick. Unfortunately, i need some help here, too. :( I've found a post from Adam, concerning tmpfs: http://os.inf.tu-dresden.de/pipermail/l4-hackers/2014/006244.html I did all it says, and of course edited anything to my concerns. But my App fails to write at /tmp. fopen("/tmp/file", "wb") == NULL Maybe i do not place the fstab-file correct. Right now, fstab is located in the MODULE_SEARCH_PATH. But building the image does also work if there is no such file. Running the image, there are no complaints about a missing fstab. Is this correct behaviour? I also added fstab to my modules.list, without success. So... Is there another way to check if fstab is loaded correctly, besides using fopen(). -------- Here my files (shorted): # fstab / /tmp tmpfs defaults # modules.list entry app-cfg kernel fiasco -serial_esc roottask moe rom/app.cfg module l4re module ned module app.cfg module fstab [...] module libmount.so module libl4revfs-fs-tmpfs.so # app.cfg ld:start( "rom/app", { FSTAB_FILE = "rom/fstab" }); # Makefile REQUIRES_LIBS = libmount libl4revfs-fs-tmpfs

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[ASK] Basic L4Re
by Erry Pradana Darajati 13 Oct '14

13 Oct '14

Hello L4 Hackers I am working on a project with L4Re in Pandaboard for my College Final Project. And right now i am in a stuck. So far, i have already know how to boot, print and read from the serial port (UART3) of pandaboard. But i can't understand the fundamental / basic of L4Re itself. Like how to make a new program outside the main program of "hello" (i am using hello code all of this time to experimenting). And also how to access the memory of the host computer using L4Re code. Because the main goal of the project i am working on is be able to access the GPIO of Pandaboard. And also, is there is any way to recompile L4Re without recompiling all of the module it use. Because in my computer it took a time to recompile even the change is only a line of code Can anyone teach or show me how to make it ? Actually i already have read the documentation of L4Re, but i am still having a hard time understanding it. Thank you for any answer and feedback. -- *Regards,* *Erry Pradana Darajati | Student of Computer Engineering* *Politeknik Elektronika Negeri Surabaya / EEPIS, Indonesia*

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L4 Bootsrap Fiasco Addr
by Wölfel, Tobias 11 Oct '14

11 Oct '14

Hello All, I am working on porting Fiasco.OC to openrisc (or1k), but are stucked at booting the kernel. The problem is that the addr in boot_info.kernel_start is pointing to the beginning of the bootsrap, and therefore it will not start the kernel. In startup.cc there is the mbi, mb_info and mb_mod, which I suppose is the place where the addr is coming from. But where is it set exactly? For or1k IMAGE_MODE is used. The output of the bootstrapping is at the end. Thanks a lot for the help, Tobias " Loading fiasco [0x1103000-0x1104000] [0x1104000-0x11040ac] [0x11040ac-0x112c340] [0x112c340-0x1134468] [0x1135000-0x1135a84] [0x1135a84-0x1136000] boot_info.kernel_start 100 Loading sigma0 [0x100000-0x107ff4] [0x108000-0x10c17c] Loading foo find kernel info page... found kernel info page at 0x1103000 Regions of list 'regions' [ 100, 1d403] { 1d304} Boot bootstrap [ 128ac, 1291e] { 73} Boot mbi [ 17000, 171ab] { 1ac} Root Multiboot info [ 1d058, 1d0af] { 58} Boot mbi [ 100000, 10c17b] { c17c} Sigma0 sigma0 [ 1100000, 11001d3] { 1d4} Root Module [ 1103000, 1135fff] { 33000} Kern fiasco API Version: (87) experimental Sigma0 config ip:00100344 sp:0001b040 Roottask config ip:00000000 sp:00000000 Starting kernel fiasco at 00000100 "

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Thread synchronization with in the same address space
by teclis High Elf 10 Oct '14

10 Oct '14

I have two threads running in the same server. On thread handles incoming ipc messages from the clients in different address spaces and the other thread does the work. The thread handling the incoming ipc needs to pass an integer value to the worker thread. Could I synchronize them using int l4util_cmpxchg32 <https://os.inf.tu-dresden.de/L4Re/doc/group__l4util__atomic.html#gacb4a5e47…> (volatile l4_uint32_t <https://os.inf.tu-dresden.de/L4Re/doc/group__l4__basic__types.html#gac1d09f…> *dest, l4_uint32_t <https://os.inf.tu-dresden.de/L4Re/doc/group__l4__basic__types.html#gac1d09f…> cmp_val, l4_uint32_t <https://os.inf.tu-dresden.de/L4Re/doc/group__l4__basic__types.html#gac1d09f…> new_val) the worker thread could then check the value of dest to get the integer. Would the worker thread need to use an atomic read function when it reads the value of dest and if so which function would the worker thread use for the atomic read? thanks,

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examples/libs/l4re/c++/shared_ds/ds_clnt.cc
by teclis High Elf 10 Oct '14

10 Oct '14

>From examples/libs/l4re/c++/shared_ds/ds_clnt.cc line 49 : L4::Cap<L4::Irq> irq = L4Re::Util::cap_alloc.alloc<L4::Irq>(); It seems this template name L4::Cap and the function name L4Re::Util::cap_alloc are a bit misleading or only designate a sub-set of the objects functionality. In this line you are not just requesting permissions but getting a Unix style file handle that you then use to issue commands to the server on line 92: irq->trigger(); Is my understanding correct? At line 49 you are opening L4 equivalent of a Unix style file handle for sending commands to a server and not requesting permissions or am I over simplifying. thanks

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contiguous memory blocks and zero copy
by teclis High Elf 09 Oct '14

09 Oct '14

How does L4Re handle contiguous memory blocks? What are the system calls used to allocate and manage contiguous memory? Is it possible to do zero copy data transfer between drivers and if so how is it done in Fiasco (so in linux world you would say no copy_to_user() and copy_from_user() ) thanks,

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l4linux shutdown cleanup
by Masti Ramya Jayaram 09 Oct '14

09 Oct '14

Dear all, I would like to perform some cleanup operations after l4linux shuts down..such as zero out all the memory it used and re-encrypt the original vmlinux image. I would like to know how I could do this from sigma0 preferably or even in the fiasco kernel. Could anyone point me to where the clean up procedure (release of resources) occurs once l4linux shuts down? Thanks, Ramya

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JDB and thread ids
by teclis High Elf 09 Oct '14

09 Oct '14

What command in JDB gives me a list of thread IDs I can use with the other thread commands. I tried the list tasks and didn't see anything that looked like a thread id.

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Re: Graphical desktop, l4con, mag
by 000SKY 09 Oct '14

09 Oct '14

>>>> > > > fbdrv | To force a specific setting use a '-m <mode>' option. >>>> > > > fbdrv | L4Re[rm]: mapping for page fault failed with -34 @1a0000 >>>> > > > pc=1006452 >>>> > > > fbdrv | L4Re: unhandled exception: pc=0x1006452 There is a way to fix it. You can modify x86-legacy.devs,as follows: VGA = Hw.Device { hid = "PNP0900"; Res.io(0x3b0, 0x3bf); -- MDA Res.io(0x3c0, 0x3df); -- EGA/VGA Res.io(0x1ce, 0x1d0); -- Vbox Res.io(0x402, 0x402); -- QEMU Debug Port Res.mmio(0xa0000, 0xbffff); --Here lost a parameters. Changed to Res.mmio(0xa0000, 0xbffff,0xc000); },

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l4-hackers October 2014