l4-hackers December 2014

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

17 participants
20 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 Are they by any chance publicly available somewhere else, or are both not to be published?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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TrustZone example on i.MX6
by Markku Ahvenjärvi 07 Jul '15

07 Jul '15

Hello hackers, I'm trying to run Fiasco.OC in secure world and Linux in non-secure world on i.MX6Q. For this I'm using the TrustZone example (pkg/examples/sys/vm-tz). To secure world I have given 128MB RAM starting from 0x10000000 and I modified the example to give NS world 256MB starting from 0x20000000. I've replaced atags with dtb of my board and it is copied to NS side like kernel and initrd. At first I encountered runtime exception, which I fixed by implementing following to arm_em_tz builds Thread::arch_ext_vcpu_enabled() { return true; } Now I'm having problems at early stages of NS boot, where Linux kernel is checking for the dtb magic. The code loads the dtb magic from the address I'm giving in r2 register (0x21000000), but the magic value usually have one byte or all of them incorrect. I've used JDB to dump the area of dtb after hitting that error and it shows the dtb magic properly. So for some reason the NS-world gets mangled value. Any idea what might be causing this? Thanks, Markku

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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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User-level objects
by li94575 23 Jan '15

23 Jan '15

Hi， As I know, we can set access permissions for the kernel objects, and access to user-level objects is through IPC_Gate. So, can I set access permissions for user-level objects through the IPC_Gate? Another question is that If multiple clients need to access a particular service object, do they use different IPC_Gate or the same?

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Is anyone has experience with pandaboard omap4460？
by Zachary 22 Jan '15

22 Jan '15

Hi, I want to buy a pandaboard to run L4Android. Dose L4Android supports omap4460? Is anyone has experience with it? Best, Zachary

5 12

Re: L4Re GPIO
by Erry Pradana Darajati 05 Jan '15

05 Jan '15

>Hi >This piece of code is missing the mapping of the GPIO4's MMIO region. For your >client program to successfully access the GPIO chip you need to create a virtual >device in IO's lua configuration file. Then you attach this device to a virtual bus. In the >startup script you hand IO's capability to that virtual bus to the 'vbus' cap of your >client. Then you client can query its vbus to discover connected devices and their >resources (see documentation of libvbus for reference). Then your client can map the >GPIO's chip MMIO region. > >Best, >Matthias. Thank you for the explanation. I am reading through the libvbus doc right now. I'm still not fully understand but if i conclude the method to access the gpio of omap4460 in Pandaboard is : Define the res.mmio(address) in lua .dev script. Make vbus capabilities in .cfg. Make a program that can access GPIO via vbus with a client-server concept? I'm sorry i'm not fully understand about this, but what is the server of this client i am making. Also, before i your email, i already 'porting' a omap4460-chip driver in io module. and editing the .devs file so it matches with the memory of omap4460 (The two file is attached). Is my step right, and after that what should i do to be able to access it via my main program. When i try to compile the omap44x2.c it give me error like attached below. Is it because i'm not insert all of the virtual function in my program ? because actually i am not really in my goal in the mean time. I really appreciate and say biggest thanks with any of your suggestion and answer P.S : I am attaching my current main program just in case. And i still access it directly. without main2.c : http://pastebin.com/eZKqy1LE omap44x2.c : http://pastebin.com/0hupnnyR arm-omap4.devs : http://pastebin.com/pK6k7F5y error output : http://pastebin.com/s2skR3wu

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Re: Iostream and string in L4Re
by Erry Pradana Darajati 05 Jan '15

05 Jan '15

Hi, I already fix the line to this line >> REQUIRES_LIBS += libc_be_file_stdin libstdc++ but it still gave error. But the error is not in the compiler. It's on the linker. My code is like this : char cmd[12] ; printf("Initialization Finished\n"); while(1) { printf("erry@erry-OS : \t"); gets(cmd); if(strcmp(cmd,"clear")==0) { ............. It gives undefined referenced error to gets in main.o (Liunker error not compiler error). Where do i go wrong. And also, how to use getline() in this scope ? >> And also, how to make hello-cfg be able to accept keyboard input. I have >> already include libc_be_file_stdin and include line below in my hello.cfg >> but it still not working : >> >> *L4.default_loader:start({ caps = { log = L4.Env.log,},l4re_dbg = >> L4.Dbg.Warn,log = { "l4linux", "yellow" },}, "rom/hello");* > >That looks ok to me. How are you trying to get the input in your >program? I'm trying to get input using getchar(). But when i load the kernel. It's still skips the input sequence and going into loop (I'm accpeting the keyboard input inside While(1)) Thank you for any help -- *Regards,* *Erry Pradana Darajati | Student of Computer Engineering* *Politeknik Elektronika Negeri Surabaya / EEPIS, Indonesia*

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Re: L4Re GPIO
by Erry Pradana Darajati 28 Dec '14

28 Dec '14

>> 1. I want to QEMU to accept input from keyboard to emulate and study how to >> use an configure of IO. I study this as a part of my main goal to access >> GPIOs of Pandaboard. Well, in my last email i stated that i already include > x86-legacy.devs module in modules.list, and define >> REQUIRES_LIBS=libc_be_file_ >stdin, and using "default-kernel fiasco >> -serial_esc" defined. But, it still not respond to any of my keyboard >> input. So, what did i miss? > >The x86-legacy.devs is for x86-based platforms. The pandaboard is ARM >based, so you do not need that file there. Also, the input here is also >based on the UART that is driven by the kernel, so there's no driver >necessary in user-land here. As already questioned in the other mail, >how are you trying to get the input in your program? Yes, I am testing this scenario in QEMU using x86 Build. The purpose of this testing is to understand how to access and use the IO using L4Re. Because i'm still not fully understand about it. So i'm trying to make a L4RE Build x86, boot it in the QEMU and directly access using keyboard input (not via serial). But i still cannot do that. In Pandaboard ARM. i am already understand and be able to access keyboard via UART3 >> 2. I have modified omap3 driver that included in the package to be used >> with omap4460 registers, but i have a few difficulties. There are few >> missing registers (like Clr_irq_enable1 register that not present in >> OMAP4460) and i am still cannot comprehend the scm_offset table. Because >> when i crossreferencing the source with the OMAP3 TRM the i cannot >> understand the value. My question is. Is it be able to use only some of the >> defined register to do simple IO task, and enable or disable register ? > >I've not written the particular code, but the scm_offset seems to select >a specific gpio block. >For starting to work on a driver I recommend to start with a simple >program and directly work on the MMIO. This helps to understand how the >device is working. When basic things work, such as switching pins >on/off, settings directions, interrupts, etc things can be integrated. I am studying to directly access the GPIO. So if i wrote simple program (let's say main.c program in testGPIO module that i created myself). I don't need to call the .devs and .io or call the driver module ? And also, i already make successful block code to access GPIO but not using L4Re API. But it cannot be implemented in L4Re Block code. It's something like this : http://pastebin.com/TMc9ieBr Thank you, and i really appreciate any answer and helps. -- *Regards,* *Erry Pradana Darajati | Student of Computer Engineering* *Politeknik Elektronika Negeri Surabaya / EEPIS, Indonesia*

2 1

Paper: undermine memory isolation in Fiasco OC covert channels
by teclis High Elf 23 Dec '14

23 Dec '14

Hi, These researchers from TU Berlin claim to be able to undermine memory isolation in Fiasco OC through the use of covert channels. I'd be very interested to hear the opinion of the Fiasco experts. (Could a system built on Fiasco be hardened against such an attack be adding access control for UDP ports)?? http://eprint.iacr.org/2014/984.pdf

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l4-hackers December 2014