September 2018 - Devel - lists.sel4.systems

seL4 test on x86
by Yevgeny Lavrov 30 Jan '25

30 Jan '25

Hello, I'm new to seL4 and I'm just doing it for learning purpose. I'm trying to run seL4 test suite or simple hello world task from seL4 tutorials on the real hardware. So far I had no problems compiling seL4 test suite and running via QEMU for both x32 and x64 platforms. However, when I try to run it on the actual hardware following Running on real hardware tutorial for x86 I end up with no output at all and no error msgs that can give me a clue on where something went wrong. After compiling seL4test for x86, I ended up with two images in sel4_dir/images/ folder. Copied them over to /boot/sel4/ folder and created a new GRUB2 entry that looks like this menuentry “seL4 test suite” --class os { load video insmod gzio insmod part_msdos insmod ext2 set root=’(hd0,msdos5)’ multiboot /boot/sel4/kernel-ia32-pc99 module /boot/sel4/sel4test-driver-image-ia32-pc99 } update grub, restart and select the new entry from GRUB menu. I end up with blinking cursor on the top-left side of the screen. Please advise.

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Stuck during invalidate local TLB in Tx2
by Muneeswaran Rajendran 16 Oct '24

16 Oct '24

Hi seL4 Dev team, Can someone explain the reason (share the reference) to invalidate the local TLB during kernel vspace activation as part CPU initialisation. The Tx2 board stuck while performing this operation. As per my understanding both Tx1 and Tx2 are using same A57 core. so the TLB initialisation and invalidation remain same for Tx2 and should not stuck during invalidation.Please correct me if anything wrong here. I understand from that instruction (tlbi vmalle1) which is invalidating stage 1 entries associated to the current VMID. Also from arm mmu code the seL4 setting up (TCR_EL1) TCR register addressing space as 48bit, ASID as 16bit and page table setup 4k granular size. I am using MRS macro to dump the spsr_el1 and dspsr_el0 register to see the state of processor but its throwing synchronous exception. Do we have any other option to dump all the register content to see the state of processor like we have one in 'sel4debug_dump_registers' which is used in sel4test code. Regards, Muneeswaran R

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Questions about Memory Management in seL4
by Daniel Wang 19 May '23

19 May '23

Hi all, Sorry to bother, I have some basic questions about seL4 memory management. Can someone help me? 1. where is the kernel’s address space? I know there are basically three methods: a) separate virtual address space, e.g. through changing page tables on entry into privileged mode to access b) physical space, e.g. through disable automatic hardware translation of virtual addresses on entry into privilege mode c) privilege region in each process’s virtual address space, e.g. through page table to map kernel address into use-mode process. My question is which of this is being used by seL4 microkernel? 2. Objects like CSpace, VSpace, CNode, TCB, Endpoint, etc. are called kernel objects, but it seems all dynamically allocated in thread running/creating time. Are those objects (e.g. Figure 3.3 in seL4 manual) in kernel space or in user space? 3. I read that after the kernel boot up, it passes all resources, untyped memory to the first thread. Are those untyped memory physical memory or virtual memory in a single page? The reason I ask is I’m learning the code of the UNSW AOS project (two of the assignment projects are implementing frame and papers). I’m confused that before the implementation of frames and pages what kind of memory is passed to the the first thread? I saw int AOS project, it uses ut_table_init(), ut_steal_mem(), I wonder what kind of memory it operates on? Thanks -Dan

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Network lwip for imx6
by wong xuguo 11 Dec '18

11 Dec '18

Hi, I am a student fron Nanjing university, a fresh man of microkernel, specially, know very little about the seL4. Recently I accept a chellange about porting the lwip to sel4, on arch of imx6, does any one could give me a clue? I found the source of camkes does have this code, could I do something to port, to make the lwip work? What my aim is make a tcp echo server. Thank you for all of you help. Best regards from Xuguo Wang

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Non CAmkES VM on x86
by Chris Guikema 08 Nov '18

08 Nov '18

DornerWorks is looking at working with the CAmkES-VM. In previous work with ARM, we've only used a non-camkes VMM, since the hypervisor pieces were more important (and 64-bit ARM CAmkES hadn't been developed). Out of curiosity, has Data61 ever worked with a non-CAmkES VM on x86 similar to how the old ARM VMM worked? If so, is that something that could be released? Thanks, Chris Guikema

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Passing Network Resource to Linux VM in TK1-SOM
by Daniel Wang 07 Nov '18

07 Nov '18

Hi all, I got a question, how can I pass the network communication to Linux virtual machine? Following the work of seL4-ARM-VMM with TK1-SOM board, i run seL4 as the microvisor that hosts the buildroot Linux as a user-land process, I was able to mount the MMC storage in the virtual machine, but I cannot get the NIC works. I’m wondering has anyone tried it that can give me some hint? Best Regards -Daniel Wang

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run docker on sel4
by Jia He 06 Nov '18

06 Nov '18

Hi all I am new comer to sel4 community. I knew a little bit virtualisation infrastructe(kvm/qemu), but I know little about sel4/docker. I am investigating the proper implemenatation for running docker on sel4 on arm64. There might several ways I can figure out.Any suggestions are welcome :-) 1. run linux on sel4 vmm (camkes_vm) and run docker on linux. This might be the easiest way. It might have worked well on X86 2. porting l4linux to sel4. Don't know whether it is feasible? 3. run docker as sel4 service without linux. On this way, golang and its library should be ported to sel4. Some missed syscalls which are needed by docker should be implemenated. Is there any other ways or anything else to make the implatation more feasible? --- Cheers, Justin

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Does seL4 provide an initrd with a shell?
by Baptiste Lepers 03 Oct '18

03 Oct '18

I have been following the instructions "Fetching, Configuring and Building seL4test" on this page https://docs.sel4.systems/GettingStarted.html. Everything seems to work, but the initrd provided only runs a bunch of tests and then exits. Is there another project that provides a shell or a way for me to launch my own programs? I have tried to follow the instructions on these pages https://docs.sel4.systems/Hardware/Qemu/ and https://docs.sel4.systems/CAmkESVM but the repo init command fails (404). Thanks, Baptiste.

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Alignment fault without U-Boot Cache Enabled
by Nicholas Pahl 29 Sep '18

29 Sep '18

Hi All, I have noticed an alignment fault in the seL4 elfloader when running seL4 on an AArch64 platform with dcache disabled in U-Boot. The alignment fault is caused by reading the elf files header in the elfloader. The fault can be fixed (hacked) by modifying the length of the elf file name, located before the elf file header, to force a proper alignment. Is the seL4 elfloader intended to be dependent on u-boot enabling the cache?

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How is undefined behavior in x86 ISA handled?
by Wean Irdeh 27 Sep '18

27 Sep '18

Hi all. I was having discussion about how secure handwritten asm code compared to C code in https://board.flatassembler.net/topic.php?p=206126#206117 and someone mentioned that there are undefined behavior in x86 instruction set How is these x86 undefined behavior handled in sel4?

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