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1384 discussions

CallWithMRs is an unexercised code path
by Jeff Waugh 27 Oct '16

27 Oct '16

Hi all, Last night I opened two pull requests to begin fixing the CallWithMRs code path on x86_64 and aarch32. syscall_stub_gen.py couldn't generate x86_64 stubs for the CallWithMRs / non-IPCBuffer path. That didn't surprise me too much, as x86_64 support is relatively new. Then I discovered that libsel4 *always* [1] uses the IPCBuffer path. Hrm. Changing that prompted a quick fix to aarch32's apparently unused, long since even built CallWithMRs. (Similar fixes might be needed in some of the other functions.) The test suite failed with it on aarch32, which I could poke at in more depth, but it worked fine for x86_64. So… what's the status of the *WithMRs functions? Based on my understanding of the source (particularly the new helper functions) and assembly output, they're destined for the chopping block, right? Thanks, Jeff [1] hard coded --buffer parameter to syscall_stub_gen.py in libsel4/Makefile, since late 2015

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Build Error
by Andrew Mine 27 Oct '16

27 Oct '16

Hi I have used sel4-tutorial branch earlier and was able to build and run earlier. I realized that my branch is way behind, so I have cloned the new branch into a separate folder and am compiling for zynq device. I get the following build error: [apps/hello-1] building... [HEADERS] [STAGE] autoconf.h [CC] src/main.o [CC] src/util.o [LINK] hello-1.elf sel4tutorials/stage/arm/zynq7000/lib/libsel4.a: error adding symbols: Archive has no index; run ranlib to add one collect2: error: ld returned 1 exit status make[1]: *** [hello-1.elf] Error 1 make: *** [hello-1] Error 2 Is anyone else facing this issue? I am using arm-none-eabi-gcc for compiling. Regards Andrew

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Allocman Error
by Neelesh Vemula 26 Oct '16

26 Oct '16

Hi I have created a new process from the root/init task. In the new process I have the following code for initializing the allocman as below: vka_t vka; allocman_t *allocman; vspace_t vspace; #define ALLOCATOR_STATIC_POOL_SIZE ((1 << seL4_PageBits) * 10) UNUSED static char allocator_mem_pool[ALLOCATOR_STATIC_POOL_SIZE]; #define ALLOCATOR_VIRTUAL_POOL_SIZE ((1 << seL4_PageBits) * 100) int main(int argc, char **argv) { allocman = bootstrap_use_current_1level(SEL4UTILS_CNODE_SLOT, CONFIG_SEL4UTILS_CSPACE_SIZE_BITS, 0, (1u << CONFIG_SEL4UTILS_CSPACE_SIZE_BITS), ALLOCATOR_STATIC_POOL_SIZE, allocator_mem_pool); allocman_make_vka(&vka, allocman); vka_object_t ep_object = {0}; error = vka_alloc_endpoint(&vka, &ep_object); ZF_LOGF_IFERR(error, "Failed to allocate new endpoint object.\n"); I have the following definition structure shared as enum sel4utils_cspace_layout { /* * The root cnode (with appropriate guard) */ SEL4UTILS_CNODE_SLOT = 1, /* The slot on the cspace that fault_endpoint is put if * sel4utils_configure_process is used. */ SEL4UTILS_ENDPOINT_SLOT = 2, SEL4UTILS_PD_SLOT = 3, FREE_SLOT = 4, }; This particular program has compiled for zynq-7000 platform and when running it I get the following output in the stdout : Just entered the user function vka_alloc_object@object.h:51 Failed to allocate object of size 16, error 1 Assertion failed: error == 0 (/apps/zynq-comm-user/src/main.c: main: 71) I have been not able to figure out why this error is occurring. I can only guess that the allocman was not initialized properly. Can someone help me with what I may have done wrong? Regards Neelesh Vemula

2 1

Exynos Arndale 5420 support
by Yevgeny Lavrov 26 Oct '16

26 Oct '16

Hello. Exynos Arndale 5250 is listed as seL4 supported ARM devices. I would like to know if seL4 also supports Exynos Arndale 5420 board, and if it does, then would the process of mounting seL4 onto Arndale 5420 be the same as with 5250? Thanks

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seL4 Call Issue
by Chris Guikema 26 Oct '16

26 Oct '16

Hello, I am working on a lock system using templates (based on what is found here: https://github.com/seL4/camkes/tree/master/apps/mutex). This system can work, but there are some issues with the components just going back and forth when calling the locks. I believe this is an issue with multiple components using the same endpoint to communicate with the "lock server" and the calls getting pre-empted by other threads. Here are the system calls that are used to hit the endpoint with the (un)lock request. seL4_Send(/*? ep ?*/, info); info = seL4_Recv(/*? ep ?*/, NULL); And in the lock server: seL4_MessageInfo_t info = seL4_Recv(/*? ep ?*/, &sender); ...do locking things seL4_Send(/*? ep ?*/, info); So in order to prevent preempting by other threads, I went and changed the (un)lock request system call to info = seL4_Call(/*? ep ?*/, info); Using print statements, I was able to determine that the lock server receives the proper message on the endpoint and performs the locking operations. However, when it reaches the seL4_Send operation, the system locks up. This shouldn't be the case, because one component is waiting on the endpoint with the seL4_Call, and the other is sending information on the same endpoint, especially when having separate Send & Recv statements works. Am I doing something incorrect? Thanks for your help, Chris Guikema

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Starting Threads in New seL4Utils processes.
by Richard Habeeb 25 Oct '16

25 Oct '16

Hello all, I am using seL4Utils to create some new processes. For these I am also transferring capabilities to some untyped kernel memory so that those processes can start their own worker threads and make endpoints. I've managed to get those threads started; however, I am a bit confused about how the CSpace is laid out now. My problem is that I want these worker threads to have capabilities to an endpoint created by the child process, but I can't figure out how to copy the cap. This is my TCB configure line. error = seL4_TCB_Configure(THREAD_2_CAP, seL4_CapNull, seL4_MaxPrio, SEL4UTILS_CNODE_SLOT, seL4_NilData, SEL4UTILS_PD_SLOT, seL4_NilData, ipc_buffer_vaddr, THREAD_2_IPC_BUF_CAP); Any guidance is appreciated. Thanks. -- Richard Habeeb Research Assistant, Computer Science, USF http://habeebr.bitbucket.org/

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timers in seL4
by Horace Blanc 24 Oct '16

24 Oct '16

Hi, I am trying to understand the timer design of both seL4 as a kernel and as a hypervisor on ARM architecture. I understand that in both cases, seL4 uses a timer in order to preempt its threads. This means that seL4 must keep the control over that timer and cannot let threads use it directly. I also understand that seL4 does not provide any timer API to its threads. It seems then that the intended use is to implement a timer driver in userland in order for other application to access timing functions. But this timer driver cannot access the same timer as seL4. Does this mean that at least two physical timers (or at least two physical timer interfaces) are necessary? ARM virtualization extensions offers a virtual timer to be used by VMs and which is implemented with an offset register. They also offer different timers (one for an hypervisor, one for kernel/application and one for the virtual timer). It seems that the current seL4 as a hypervisor project does not use these extenstions. Do they? If not why? Thank you for your answers

1 0

Freelance
by Marco Reus 22 Oct '16

22 Oct '16

Hi I apologize if this is not the right platform to reach people. But I am looking for a freelancer who has some expereince in working with seL4 kernel. I need some aid in implementation of a project. Regards Vicky

1 0

Larger badges on 64-bit?
by Corey Richardson 21 Oct '16

21 Oct '16

Is there a future in which we recover the extra 32+ bits of padding on 64-bit systems for use in badges? In Robigalia, 28 bit badges are extremely limiting for what we want to use them for. -- cmr http://octayn.net/

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CAmkES Groups
by Robert VanVossen 19 Oct '16

19 Oct '16

Hello, I have been trying to get groups with CAmkES 2.2 working, but it doesn't look like it will build correctly. At first, when I place components in a group, I get that there is an unresolved reference to one of the components during compilation. I was able to get past this by moving the function assign_address_spaces in camkes/camkes/runner/Transforms.py from POST_RESOLUTION to PRE_RESOLUTION, but after that I still ran into some issues: [LD] MyGroup_group_bin if [ 2 -eq 1 ]; then cp "comp1.instance-copy.bin" " MyGroup_group_bin"; else /usr/bin/ccache arm-xilinx-eabi-gcc comp1.instance-copy.bin comp2.instance-copy.bin -Wl,--build-id=none -L<stage_dir>/lib -Wall -nostdinc -std=gnu11 -O2 -D_XOPEN_SOURCE=700 -marm -Wtrampolines -mcpu=cortex-a9 -g -Wno-main -fno-stack-protector -Wl,--start-group -lsel4 -lsel4debug -lc -lsel4muslccamkes -lsel4camkes -lsel4sync -lutils -lsel4vka -lsel4utils -lsel4platsupport -lplatsupport -lsel4vspace -lgcc -Wl,--end-group -static -nostdlib -u _camkes_start -e _camkes_start -o MyGroup_group_bin; fi <stage_dir>/lib/libsel4camkes.a(crt0.o): In function `_camkes_start': (.text+0x6c): undefined reference to `_start' Any insight on this? Are groups supported yet? Thanks, Robbie VanVossen

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