Devel July 2021

devel@sel4.systems

23 participants
20 discussions

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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VM Kernel Modules
by Michael Neises 20 Nov '21

20 Nov '21

Hello all, I recently spent a lot of time getting the camkes-vm-linux tutorial to work, because it is the only example I could find of compiling a kernel module for the linux vm as a part of the camkes build process. Unfortunately, the kernel module doesn't seem to work. For more information, see the previous email chain as well as https://github.com/NeisesResearch/vm_measure/wiki/Building-the-camkes_vm_li… . In lieu of doing things the right way, I believe I could compile a kernel module for the linux kernel that is provided as part of the camkes build system. I believe this is how the introspect-app accomplishes its work. However, I need to have the exact kernel and exact configuration in order to compile the kernel module correctly. Can anyone point me to the correct kernel version and configuration, so that I can target the provided linux kernel for module compilation? Or if there's a better way to get a kernel module in there, please let me know. Cheers, Michael Neises

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ethernet pass-through using CAmkES VM on x86
by meshkat os 29 Sep '21

29 Sep '21

hi I am new to camkes VM on x86. I want to connect the guest to the host via the ethernet network. and I used this ( https://docs.sel4.systems/projects/camkes-vm/) tutorial to create pass-through in minimal example x86. run in qemu on ubuntu 17.10. but the guest os doesn't create an ethernet interface. I also tested zmq example this is qemu options: qemu-system-x86_64 -machine q35,accel=kvm,kernel-irqchip=split -cpu Nehalem,+vme,+pdpe1gb,-xsave,-xsaveopt,-xsavec,-fsgsbase,-invpcid,enforce,+vmx -nographic -serial mon:stdio -m size=2G -enable-kvm -net nic,model=e1000 -net tap,script=no,ifname=tap0 -kernel images/kernel-ia32-pc99 -initrd images/capdl-loader-image-ia32-pc99 and minimal.camkes configs: configuration { VM_CONFIGURATION_DEF() VM_PER_VM_CONFIG_DEF(0) vm0.simple_untyped23_pool = 20; vm0.heap_size = 0x2000000; vm0.guest_ram_mb = 128; vm0.kernel_cmdline = VM_GUEST_CMDLINE; vm0.kernel_image = "bzimage"; vm0.kernel_relocs = "bzimage"; vm0.initrd_image = "rootfs.cpio"; vm0.iospace_domain = 0x0f; vm0_config.pci_devices_iospace = 1; vm0_config.ioports = [ {"start":0x4080, "end":0x4090, "pci_device":0x1f, "name":"SATA"}, {"start":0x4090, "end":0x40a0, "pci_device":0x1f, "name":"SATA"}, {"start":0x40b0, "end":0x40b8, "pci_device":0x1f, "name":"SATA"}, {"start":0x40b8, "end":0x40c0, "pci_device":0x1f, "name":"SATA"}, {"start":0x40c8, "end":0x40cc, "pci_device":0x1f, "name":"SATA"}, {"start":0x40cc, "end":0x40d0, "pci_device":0x1f, "name":"SATA"}, {"start":0x3000, "end":0x3020, "pci_device":0, "name":"Ethernet5"}, ]; vm0_config.pci_devices = [ { "name":"SATA", "bus":0, "dev":0x1f, "fun":2, "irq":"SATA", "memory":[], }, { "name":"Ethernet5", "bus":5, "dev":0, "fun":0, "irq":"Ethernet5", "memory":[ {"paddr":0xc0500000, "size":0x20000, "page_bits":12}, {"paddr":0xc0520000, "size":0x4000, "page_bits":12}, ], }, ]; vm0_config.irqs = [ {"name":"SATA", "source":19, "level_trig":1, "active_low":1, "dest":11}, {"name":"Ethernet5", "source":0x11, "level_trig":1, "active_low":1, "dest":10}, ]; } thanks

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Operating Systems built on top of seL4
by Sidhartha Agrawal 02 Aug '21

02 Aug '21

Hello sel4-devs, I am a first-year graduate student at the University of British Columbia at their Systopia Lab <https://systopia.cs.ubc.ca/> working on operating systems research. My advisor is Prof. Margo Seltzer <https://www.seltzer.com/margo>. In a past life, I have worked as a software engineer at Oracle and Arista Networks. My research is on General Purpose Isolation Mechanism in the OS. We ask whether we really need to have N different isolation mechanisms or whether instead, we could develop a framework in which all these different mechanisms represent points on a continuum. Here is a write-up <https://sid-agrawal.ca/#research-projects> with some more details. I am using seL4 as the microkernel base to build my research idea. At this stage, I am not looking in to the formal verification aspect of seL4, but that might change once I have a better idea about the type of mechanism I want to build. I would also like to keep the changes in the kernel to be minimum and try to demonstrate my ideas using user space processes. I have tried out the tutorials on the seL4 website. Currently, I am wading through the different helper libraries in seL4/seL4_libs <https://github.com/seL4/seL4_libs>. As someone who is just starting with seL4 ecosystem, I had a few high-level questions: - Are there are example OSes built with seL4, which would be a good place to look at? Specifically, I am looking for components such as basic versions of a process-server, vm-server, pager, file-systems server. - I came across refOS <https://github.com/seL4/refos>, but wasn't sure if it is still being maintained. - Another option was Genode <https://genode.org/documentation/general-overview/index>. This seemed to be maintained by another community and has many layers of abstractions since it supports multiple kernel backends. I am looking forward to engaging with this community, learning about seL4 and making meaningful contributions. Best, Sid sid-agrawal.ca

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Sel4 rumprun has issues compiling
by Vortex 01 Aug '21

01 Aug '21

Hello, I would like to bring this issue to the attention of the community. Sel4’s fork of the rumprun unikernel no longer compiles. Due to the usage of Werror flag, the compiler produces repeated warnings which in turn creates errors. It seems like the rump kernel was tested on an older version of gcc and because it is older, raises warnings and causes the build to fail on newer compilers. This is a similar issue to https://github.com/rumpkernel/rumprun/issues/82 I have tested rumprun in the sel4 docker container. My build logs are also attached to this email. Thank you for taking attention to this issue. Sincerely, Ellis

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Docker for ARM?
by dave＠synergy.org 27 Jul '21

27 Jul '21

I recently moved and my x86-64 machines are in storage. Are there docker images for Debian ARM/32 or Raspbian I can use to build seL4 on my Raspberry Pi? It is my target platform. Thanks, Dave

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Camkes and native tcp/ip and networking
by Amirreza Zarraby 27 Jul '21

27 Jul '21

Hello seL4 team, I am try trying to use camkes to write a simple firewall. I am wondering if you can direct me to any existing camkes project which uses tcp/ip and network driver that I can look into as starting point. There is a seL4 based webserver but it seems to use vm and Linux. Thank you for your time. - Amir

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Jetson AGX Xavier board porting
by bobding＠msn.com 27 Jul '21

27 Jul '21

Has anyone ported to Nvidia AGX Xavier board?

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camkes-vm-examples-manifest cma34cr_centos fails
by christinefragoso＠protonmail.com 27 Jul '21

27 Jul '21

Hello, I'm trying to run the cma34cr_centos application from camkes-vm-examples-manifest, but I get this error: "Kernel entry via Unknown syscall, word: 65". I've set up VMware as described at https://docs.sel4.systems/Hardware/VMware/. In camkes-vm-examples-manifest/cma34cr_centos_x86_build, I've built the kernel: ../init-build.sh -DCAMKES_VM_APP=cma34cr_centos Then I ran these commands: ninja sudo ./seL4vmw.py images/kernel-x86_64-pc99 images/capdl-loader-image-x86_64-pc99 vmrun -T player start $HOME/vmware/seL4/seL4.vmx while :; do socat -d -d UNIX-CONNECT:/tmp/vsock,forever PTY,link=/tmp/mytty done After VMware boots, I ran minicom in a separate terminal to see the serial output: minicom -D /tmp/mytty Here is the full log: Welcome to minicom 2.7.1 OPTIONS: I18n Compiled on Dec 23 2019, 02:06:26. Port /tmp/mytty, 08:47:50 Press CTRL-A Z for help on special keys Boot config: debug_port = 0x3f8 Boot config: disable_iommu = false Detected 1 boot module(s): module #0: start=0xcf3000 end=0x3821bb8 size=0x2b2ebb8 name='' Parsing GRUB physical memory map Physical Memory Region from 0 size 9f800 type 1 Physical Memory Region from 9f800 size 800 type 2 Physical Memory Region from dc000 size 24000 type 2 Physical Memory Region from 100000 size bfde0000 type 1 Adding physical memory region 0x100000-0xbfee0000 Physical Memory Region from bfee0000 size 1f000 type 3 Physical Memory Region from bfeff000 size 1000 type 4 Physical Memory Region from bff00000 size 100000 type 1 Adding physical memory region 0xbff00000-0xc0000000 Physical Memory Region from f0000000 size 8000000 type 2 Physical Memory Region from fec00000 size 10000 type 2 Physical Memory Region from fee00000 size 1000 type 2 Physical Memory Region from fffe0000 size 20000 type 2 Physical Memory Region from 100000000 size 140000000 type 1 Adding physical memory region 0x100000000-0x240000000 Got VBE info in multiboot. Current video mode is 16703 ACPI: RSDP paddr=0xf6a00 ACPI: RSDP vaddr=0xf6a00 ACPI: RSDT paddr=0xbfeee733 ACPI: RSDT vaddr=0xbfeee733 Warning: Your kernel was not compiled for the current microarchitecture. Kernel loaded to: start=0x100000 end=0xc1f000 size=0xb1f000 entry=0x100300 ACPI: RSDT paddr=0xbfeee733 ACPI: RSDT vaddr=0xbfeee733 ACPI: FADT paddr=0xbfefef67 ACPI: FADT vaddr=0xbfefef67 ACPI: FADT flags=0x21 ACPI: 0 IOMMUs detected ACPI: MADT paddr=0xbfeee937 ACPI: MADT vaddr=0xbfeee937 ACPI: MADT apic_addr=0xfee00000 ACPI: MADT flags=0x1 ACPI: MADT_APIC apic_id=0x0 ACPI: MADT_APIC apic_id=0x2 ACPI: MADT_APIC apic_id=0x4 ACPI: Not recording this APIC, only support 2 ACPI: MADT_APIC apic_id=0x6 ACPI: Not recording this APIC, only support 2 ACPI: MADT_APIC apic_id=0x8 ACPI: Not recording this APIC, only support 2 ACPI: MADT_APIC apic_id=0xa ACPI: Not recording this APIC, only support 2 ACPI: MADT_APIC apic_id=0xc ACPI: Not recording this APIC, only support 2 ACPI: MADT_APIC apic_id=0xe ACPI: Not recording this APIC, only support 2 ACPI: MADT_IOAPIC ioapic_id=1 ioapic_addr=0xfec00000 gsib=0 ACPI: MADT_ISO bus=0 source=0 gsi=2 flags=0x5 ACPI: 2 CPU(s) detected ELF-loading userland images from boot modules: size=0x3fab000 v_entry=0x408828 v_start=0x400000 v_end=0x43ab000 p_start=0x3822000 p_end=0x77cd000 Moving loaded userland images to final location: from=0x3822000 to=0xc1f000 size=0x3fab000 Starting node #0 with APIC ID 0 Mapping kernel window is done Starting node #1 with APIC ID 2 Booting all finished, dropped to user space create_object@main.c:673 [Cond failed: err != seL4_NoError] Failed to find device frame/untyped at paddr = 0xb0000000 seL4 root server abort()ed Debug halt syscall from user thread 0xffffff823e027400 "rootserver" halting... Kernel entry via Unknown syscall, word: 65 Any idea what's wrong? I just want to get one x86 application with cross VM connectors working. The other x86 applications (optiplex9020, cma34cr_ubuntu, zmq_samples) in camkes-vm-examples-manifest don't work for other reasons.

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Formally verified AES C code
by Hugo V.C. 20 Jul '21

20 Jul '21

Hi all, I don't want to use SSL/openssl in a project I'm working. Thus, I want to just use my own encryption at the app layer. As performance is not a problem (just very small data packets over a socket) I would like to have the most simple implementation possible of AES, preferably, formally verified. Is anyone aware of any public AES encrytion implementation in C that has been formally or semi-formally verified? Thank you!

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Devel July 2021