May 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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Questions on U-boot Verified Boot with CAmkES-ARM-VM
by Daniel Wang 10 Jul '18

10 Jul '18

Hi all, I’m trying to test secure boot with the CAmkES-arm-vm. I found that U-boot has its implementation of secure boot called verified boot, but it seems only support FIT image format. I’m wondering is there a way to convert the final ELF image to an FIT image? I’m studying the details of different booting image format. I’m not sure how it would work with seL4 camkes demo specifically, since there are so many binary files and cpio archives packed in the final ELF image. Would love to hear your opinions. Thank you very much! Best Regards -Daniel Wang

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sel4 qemu x86 runtime error
by Thad Seeberger 10 Jul '18

10 Jul '18

Compile now no problem however I'm getting error when running. I believe its an invalid opcode exception. I think my build not matching the qemu but I've tried diff machines and they do the same. I also get this warning during build, not sure if this relevant: Warning: Installation path /home/maddthad/camkes-tutorials-manifest/projects/capdl/capDL-tool not found on the PATH environment variable. make: Leaving directory `/home/maddthad/camkes-tutorials-manifest/projects/capdl/capDL-tool' Qemu commanr, lines with ????? suspect: qemu-system-i386 -nographic -m 512 -kernel images/kernel-ia32-pc99 -initrd images/capdl-loader-experimental-image-ia32-pc99 (process:98550): GLib-WARNING **: gmem.c:483: custom memory allocation vtable not supported Boot config: parsing cmdline 'images/kernel-ia32-pc99 ' Boot config: console_port = 0x3f8 Boot config: debug_port = 0x3f8 Boot config: disable_iommu = false ???? Warning: Your kernel was not compiled for the current microarchitecture. Parsing GRUB physical memory map Physical Memory Region from 0 size 9fc00 type 1 Physical Memory Region from 9fc00 size 400 type 2 Physical Memory Region from f0000 size 10000 type 2 Physical Memory Region from 100000 size 1fefe000 type 1 Adding physical memory region 0x100000-0x1f800000 Physical Memory Region from 1fffe000 size 2000 type 2 Physical Memory Region from fffc0000 size 40000 type 2 Multiboot gave us no video information Kernel loaded to: start=0x100000 end=0x160000 size=0x60000 entry=0x10005e ACPI: RSDP paddr=0xf7180 ACPI: RSDP vaddr=0xdfcf7180 ACPI: RSDT paddr=0x1ffffbc1 ACPI: RSDT vaddr=0xdffffbc1 ACPI: FADT paddr=0x1ffff1c0 ACPI: FADT vaddr=0xdffff1c0 ACPI: FADT flags=0x80a5 ACPI: 0 IOMMUs detected ACPI: MADT paddr=0x1ffffb11 ACPI: MADT vaddr=0xdffffb11 ACPI: MADT apic_addr=0xfee00000 ACPI: MADT flags=0x1 ACPI: MADT_APIC apic_id=0x0 ACPI: MADT_IOAPIC ioapic_id=0 ioapic_addr=0xfec00000 gsib=0 ACPI: MADT_ISO bus=0 source=0 gsi=2 flags=0x0 ACPI: MADT_ISO bus=0 source=5 gsi=5 flags=0xd ACPI: MADT_ISO bus=0 source=9 gsi=9 flags=0xd ACPI: MADT_ISO bus=0 source=10 gsi=10 flags=0xd ACPI: MADT_ISO bus=0 source=11 gsi=11 flags=0xd ACPI: 1 CPU(s) detected Detected 1 IOAPICs, but configured to use PIC instead Detected 1 boot module(s): module #0: start=0x161000 end=0x25aed0 size=0xf9ed0 name='images/capdl-loader-experimental-image-ia32-pc99' ELF-loading userland images from boot modules: size=0x189000 v_entry=0x804f544 v_start=0x8048000 v_end=0x81d1000 p_start=0x25b000 p_end=0x3e4000 Moving loaded userland images to final location: from=0x25b000 to=0x160000 size=0x189000 Starting node #0 with APIC ID 0 Booting all finished, dropped to user space Caught cap fault in send phase at address 0x0 while trying to handle: ?????? user exception 0x6 code 0x0 in thread 0xff3f5d00 "rootserver" at address 0x805130e With stack: 0x80cfda0: 0x0 0x80cfda4: 0x0 0x80cfda8: 0x0 0x80cfdac: 0x0 0x80cfdb0: 0x0 0x80cfdb4: 0x0 0x80cfdb8: 0x0 0x80cfdbc: 0x0 0x80cfdc0: 0x0 0x80cfdc4: 0x0 0x80cfdc8: 0x0 0x80cfdcc: 0x0 0x80cfdd0: 0x0 0x80cfdd4: 0x0 0x80cfdd8: 0x0 0x80cfddc: 0x0 QEMU: Terminated Have a great day.

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ARM Vchan Error
by Daniel Wang 10 Jul '18

10 Jul '18

Hi all, I’m trying to make Vchan work on camkes-arm-vm in the process I encountered a couple problems. Hope you can give me some advice. I knew that Vchan is out dated and never finished on ARM. But it seems the only option for now (please correct me if I’m wrong). Here is what I did so far: 1. modified tk1_vmlinux.c by adding the virtual device and fault handler and installed it to guest linux with vm_add_device(vm, &vchan_dev); --------------------------------------------------- vchan_device_fault_handler(struct device* d UNUSED, vm_t* vm, fault_t* fault){ //uint32_t data = fault_get_data(fault); uint32_t data = fault_get_ctx(fault)->r1; vchan_entry_point(vm, data); // fflush(stdout); advance_fault(fault); return 0; } struct device vchan_dev = { .devid = DEV_CUSTOM, .name = "vchan-driver", .pstart = 0x2040000, .size = 0x1000, .handle_page_fault = &vchan_device_fault_handler, .priv = NULL, }; --------------------------------------------------- 2. compiled linux-tegra using buildroot (by the way the current linux-tegra is 4.9.0 which is not supported by buildroot-2016, the earliest version works for me is buildroot-2017-2), added a vmm-manager kernel driver similar to the one in camkes-x86-vm. But I changed the call_into_hypervisor() to the following: --------------------------------------------------- int call_into_hypervisor(int cmd, void *data, size_t sz, vmcall_args_t *vmcall) { int res = 0; int err; unsigned phys_ptr = virt_to_phys(vmcall); vmcall->data = data; vmcall->cmd = cmd; vmcall->phys_data = virt_to_phys(data); vmcall->size = sz; down(&hyp_sem); /* Set up arguments for the ARM hyp call */ asm volatile ("mov r0, %0; mov r1, %1" : : "r" (VMM_MANAGER_TOKEN), "r" (phys_ptr): "%r0", "%r1"); asm volatile (".arch_extension virt\n\t” "hvc #0"); asm volatile ("mov %0, r0" : "=r" (res) : : ); err = vargs->err; up(&hyp_sem); return err; } --------------------------------------------------- The kernel built and run correctly. But when I try to install the kernel driver. It crashed with following information. --------------------------------------------------- # modprobe driver.ko [81.826621] driver: loading out-of-tree module taints kernel Bad sys call from [Linux]: scone 0 at PC: 0xbf000214 Assertion failed” !err (/camkes-arm-vm/libs/libsel4arm-vmm/src/vm.c: vm_event: 407) ————————————————————————— I’m not sure if this error is triggered by the modified call_into_hypervisor() or by event_thread_run()->eventfd_signal(). Any help would be appreciated! Thanks in advance. Best Regards -Daniel Wang

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IPC
by tj5527 04 Jul '18

04 Jul '18

Searching on the sel4 repository, I find there is a manual talking about IPC (https://github.com/seL4/seL4/blob/9dba8e67ccb54e207bbec22e25f21c65e5c6a45f/…) In addition to this material, where - particularly source code - would be a good start point to look into IPC design and implementation? Thanks

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seL4_Wait crash if kernel is compiled with -O0 (qemu, pc99, gcc 4.8.2)
by Fabrizio Bertocci 25 May '18

25 May '18

Hi, After hours of debugging I have discovered a quite nasty issue where seL4_Wait() crash if I build the kernel without optimization (gcc option -O0) on a pc99 tested with qemu. How to reproduce: Just create an endpoint (from a vka) and call seL4_Wait(). The simplest reproducer can be obtained from the hello-2 tutorial: - Copy the main.c from the solution directory in the apps/hello-2/src/main.c - Add the following codes right after the creation of vka (TASK 5, approx line 150): { printf("WAITING----------------------------------------------\n"); seL4_Word myBadge; vka_object_t ep_object = {0}; error = vka_alloc_endpoint(&vka, &ep_object); ZF_LOGF_IFERR(error, "Failed to allocate new endpoint object.\n"); seL4_Wait(ep_object.cptr, &myBadge); printf("---------------------------------------------- DONE!!\n"); } Essentially the added code, creates an endpoint using vka and calls seL4_Wait() on it... I expect the code to block forever since there are no other threads that can unblock it... - Build it and run it with: make pc99_hello-2_defconfig make make simulate Expected output: Booting all finished, dropped to user space 4 untypeds of size 12 4 untypeds of size 13 [...] 6 untypeds of size 29 WAITING---------------------------------------------- - Now change the configuration using 'make menuconfig' and select: seL4 Kernel -> Build Options -> Compiler optimisation flag (-O2) and change it to -O0, save the new configuration. - Rebuild and run: make simulate Now you get a kernel exception: [...] 6 untypeds of size 29 WAITING---------------------------------------------- ========== KERNEL EXCEPTION ========== Vector: 0xd ErrCode: 0xa658 IP: 0xe0118ce5 SP: 0xffaf7e28 FLAGS: 0x86 CR0: 0x8001003b CR2: 0x0 (page-fault address) CR3: 0x142000 (page-directory physical address) CR4: 0x100290 Stack Dump: *0xffaf7e28 == 0xe011a658 *0xffaf7e2c == 0x0 *0xffaf7e30 == 0x0 *0xffaf7e34 == 0xe011a658 *0xffaf7e38 == 0x8 *0xffaf7e3c == 0x202 *0xffaf7e40 == 0x0 *0xffaf7e44 == 0x0 *0xffaf7e48 == 0x10 *0xffaf7e4c == 0x7 *0xffaf7e50 == 0x0 *0xffaf7e54 == 0x0 *0xffaf7e58 == 0x0 *0xffaf7e5c == 0x0 *0xffaf7e60 == 0x0 *0xffaf7e64 == 0x0 *0xffaf7e68 == 0x0 *0xffaf7e6c == 0x0 *0xffaf7e70 == 0x0 *0xffaf7e74 == 0x0 Halting... halting... Kernel entry via Interrupt, irq 157 Version info: - gcc: gcc (GCC) 4.8.5 20150623 (Red Hat 4.8.5-11) - qemu: QEMU emulator version 2.0.0, Copyright (c) 2003-2008 Fabrice Bellard - Build environment: CentOS Linux release 7.3.1611 (Core) Other info: - gcc 4.8.5 doesn't seem to support the 'Nehalem' x86 microarchitecture, so I am selecting the 'Generic' microarchitecture (Toolchain Options -> X86 microarchitecture) - Even the tutorial 'hello-timer' fails exactly with the same exception without any modifications if you build the kernel with -O0. - Tested on a Beaglebone black: no problems compiling kernel with -O0 Regards, Fabrizio Bertocci Real-Time Innovations, Inc.

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Tutorials broken?
by Fabrizio Bertocci 22 May '18

22 May '18

Hi all, I was going through the tutorials, unfortunately I've been finding very challenging to follow the instructions as I keep encountering issues after issue. First, the repo command seems to be incorrect. In document: https://docs.sel4.systems/Tutorials/ it says: repo init -u https://github.com/SEL4PROJ/sel4-tutorials-manifest -m sel4-tutorials.xml but the manifest file 'sel4-tutorials.xml' does not exist on the git repository (of the sel4-tutorial-manifest). What is the correct manifest file to use? There are two manifests (in any branch and tag): master.xml and default.xml. default.xml seems to use the 'new' format of identifying the individual versions of the libraries (through the hash). Let's assume the correct manifest to use is the 'default.xml' from the 'sel4-tutorials' branch and initialize the workspace with: repo init -u https://github.com/SEL4PROJ/sel4-tutorials-manifest -b sel4-tutorials repo sync So, now: first tutorial, ok (but this tutorial does very little). Second tutorial (hello-2), not so good... to avoid mistake, I am copying directly the solution into the app area: cp projects/sel4-tutorials/solutions/hello-2/src/main.c apps/hello-2/src/main.c make pc99_hello-2_defconfig make ... and the build fails with: [...]/workspaces/sel4-tutorials-2/stage/x86/pc99/lib/libsel4allocman.a(virtual_pool.o): In function `_add_page': [...]/workspaces/sel4-tutorials-2/libs/libsel4allocman/src/mspace/virtual_pool.c:52: undefined reference to `vspace_get_map_obj' The missing function appears to be part of libsel4vspace, that is missing from the library dependency list. Let's add it to add it to the apps/hello-2/Makefile: diff --git a/exercises/hello-2/Makefile b/exercises/hello-2/Makefile index 25c0b35..97a4fc6 100644 --- a/exercises/hello-2/Makefile +++ b/exercises/hello-2/Makefile @@ -28,6 +28,7 @@ ASMFILES += $(patsubst $(SOURCE_DIR)/%,%,$(wildcard $(SOURCE_DIR)/src/plat/${PLA # Libraries required to build the target LIBS = c sel4 sel4muslcsys \ sel4simple sel4vka sel4allocman \ + sel4vspace \ sel4platsupport platsupport \ utils sel4simple-default sel4utils sel4debug Now it builds successfully, unfortunately when running, the child thread doesn't appear to run at all. This is the output of qemu running 'make simulate': Booting all finished, dropped to user space 4 untypeds of size 12 5 untypeds of size 13 5 untypeds of size 14 4 untypeds of size 15 4 untypeds of size 16 4 untypeds of size 17 4 untypeds of size 18 5 untypeds of size 19 5 untypeds of size 20 2 untypeds of size 21 4 untypeds of size 22 4 untypeds of size 23 2 untypeds of size 24 3 untypeds of size 25 3 untypeds of size 26 3 untypeds of size 27 1 untypeds of size 28 6 untypeds of size 29 main: hello world I would have expected seeing on the output the string 'thread_2: hallo wereld' somewhere... Why the thread 2 does not run? This code was working last time I checked (version 5.2). I tried then to continue testing the tutorials, and I went to the hello-3. Hello-3 is based on the Hello-2 but adds an endpoint for IPC between the main thread and the child thread. Surprisingly, this app not only builds out of the box without errors (apparently libsel4vspace was already added to its Makefile), but even running it, works as expected: Booting all finished, dropped to user space 3 untypeds of size 12 5 untypeds of size 13 5 untypeds of size 14 4 untypeds of size 15 4 untypeds of size 16 4 untypeds of size 17 4 untypeds of size 18 5 untypeds of size 19 5 untypeds of size 20 2 untypeds of size 21 4 untypeds of size 22 4 untypeds of size 23 2 untypeds of size 24 3 untypeds of size 25 3 untypeds of size 26 3 untypeds of size 27 1 untypeds of size 28 6 untypeds of size 29 main: hello world thread_2: hallo wereld thread_2: got a message 0x6161 from 0x61 main: got a reply: 0xffff9e9e Right now I suspect that seL4_TCB_Configure() does not work correctly if we don't provide an endpoint (because that's essentially the main difference between the two tests). Can somebody try to run the tutorials and perhaps confirm the problem? Regards, Fabrizio Bertocci Real-Time Innovations, Inc. Sunnyvale, CA

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docker build error
by Paolo Crisafulli 18 May '18

18 May '18

Hi all, I'm using the docker build environment provided by https://github.com/SEL4PROJ/seL4-CAmkES-L4v-dockerfiles Currently, "make sel4" fails with this message: E: Package 'ncurses-dev' has no installation candidate Anyone experimenting the same behaviour? Cheers, Paolo

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