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Re: Tutorial Problem
by Kent Mcleod 08 Jul '21

08 Jul '21

On Wed, Jun 30, 2021 at 11:53 AM Michael Neises <neisesmichael(a)gmail.com> wrote: > > Kent, > > > > I tried using those extra arguments and got the same error regarding kvm I reported a few minutes ago: > > > > ./simulate: qemu-system-x86_64 -machine q35,accel=kvm,kernel-irqchip=split -cpu Nehalem,+vme,+pdpe1gb,-xsave,-xsaveopt,-xsavec,-fsgsbase,-invpcid,+syscall,+lm,enforce,+vmx -nographic -serial mon:stdio -m size=2G -enable-kvm -device intel-iommu,intremap=off -net nic,model=e1000 -net tap,script=no,ifname=tap0 -kernel images/kernel-x86_64-pc99 -initrd images/capdl-loader-image-x86_64-pc99 Could not access KVM kernel module: No such file or directory > > qemu-system-x86_64: failed to initialize KVM: No such file or directory > There are instructions on how to setup KVM and nested virtualization on the tutorial that I've pasted here: "Note if you are using QEMU it is important to ensure that your host machine has VT-x support and KVM (https://www.linux-kvm.org/page/Main_Page) installed. You also need to ensure you have enabled nested virtulisation with KVM guests as described here (https://www.linux-kvm.org/page/Nested_Guests)" A quick way to check if nested virtualization is enabled (and therefore supported) on your host is to run `cat /sys/module/kvm_intel/parameters/nested`. `Y` should be returned if it's enabled. It may be easier to run the image on an actual machine instead of in qemu. The images produced can be loaded by a multiboot loader such as grub or pxelinux. (https://docs.sel4.systems/Hardware/VMware/#add-grub2-option-to-run-sel4) has an example grub config.

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seL4 Linux guest mmap() crashes the VM
by Hugo V.C. 01 Jul '21

01 Jul '21

Hi, my seL4 Linux VM box just crashed when trying to access a memory address. Basically I simply wanted to use "devmem" tool to just print the content of a specific address in memory and looked like seL4 was unable to handle the guest OS mmap() correctly. Below the console log: # ls /proc/283/maps /proc/283/maps # cat /proc/283/maps 00400000-00532000 r-xp 00000000 00:02 6023 /bin/lighttpd 00541000-00543000 r--p 00131000 00:02 6023 /bin/lighttpd 00543000-00546000 rw-p 00133000 00:02 6023 /bin/lighttpd 00546000-0054d000 rw-p 00000000 00:00 0 0bd0b000-0bd2d000 rw-p 00000000 00:00 0 [heap] 0bd2d000-0bd91000 rw-p 00000000 00:00 0 [heap] ffff82084000-ffff82085000 r--p 00000000 00:00 0 [vvar] ffff82085000-ffff82086000 r-xp 00000000 00:00 0 [vdso] ffffe6c58000-ffffe6c79000 rw-p 00000000 00:00 0 [stack] # devmem 0xffffe6c58000 8 _utspace_split_alloc@split.c:266 Failed to find any untyped capable of creating an object at address 0xffffe6c58000 map_page@mapping.c:68 Failed to map page at address 0xffffe6c58000 with cap 396187, error: 1 sel4utils_map_page_pd@vspace.c:153 Error mapping pages, bailing: 1 map_vm_memory_reservation@guest_memory.c:477 Failed to map address 0xe6c58000 into guest vm vspace vm_map_reservation@guest_memory.c:510 Failed to map vm reservation: Error when mapping into VM's vspace -------- Pagefault from [Linux]: read fault @ PC: 0x414c38 IPA: 0xffffe6c58000, FSR: 0x93020004 Context: x0: 0xffff9cfe6000 x1: 0x0 x2: 0x0 x3: 0x1 x4: 0x3 x5: 0xffffe6c58000 x6: 0x5 x7: 0x20 x8: 0xde x9: 0xffffe539cf54 x10: 0xffff9cfe8050 x11: 0x1 x12: 0x436 pc: 0x414c38 x14: 0xffffffff sp: 0xffffe539bb70 spsr: 0x60000000 x13: 0x1 x15: 0x3 x16: 0xffff9cf486c8 x17: 0x4c3870 x18: 0x0 x19: 0x8 x20: 0x0 x21: 0x4c3000 x22: 0xffffe539bd98 x23: 0xffffe6c58000 x24: 0x0 x25: 0x0 x26: 0x0 x27: 0x0 x28: 0x0 x29: 0xffffe539bc60 x30: 0x414bac m-------- main_continued@main.c:1134 Failed to run VM Halting... My three concerns here are: 1) Why this guest mmap() is crashing the VM? Memory address is valid (just guest user space process stack). 2) Is it possible to have some kind of "dump and reboot VM" when a VM and/or guest OS crashes? 3) Are there any plans to formally verify the seL4's VM camkes code? Thank you!

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Camkes SerialServer and util_libs/libplatsupport with ODROID-C4
by Robert Reid 01 Jul '21

01 Jul '21

Hi everyone Summary - trying to get util_libs/libplatsupport going for a HardKernel ODROID-C4, using the camkes serialserver_polling app - but not having any luck with mapping the UART. I'd welcome any explanations of what you think is happening here. The background and my progress follows. I thought I'd dive into the seL4 world and do some experimenting. I thought a good place to start would be the UNSW AOS project (17 years after I first did it) - but with no more ODROID-C2, got a hold of an ODROID-C4 and figured that would be a good project in itself (and well timed with a Sydney lockdown). So - good news: The peripheral devices we need are all very similar to a C2, so by getting a new DTS file and updating a few addresses it starts off fairly happily. sel4-test builds and runs (All is well...); so does the camkes adder app; and with some mods to provide enough slots (maybe because it has 4GB rather than 2GB) I have got the AOS milestone 0 stub to run (including the uart initialisation). (More work to actually finish m0 and keep going, but a job for later) But then: I moved onto the util_libs / libplatsupport project to try and port over as much of the device settings as possible; and using the camkes app serialserver_polling, under the hood using SerialServer, I can't get the uart to initialiise (or more strictly can't get the uart address to map). chardev_map / ps_io_map fails, returning a vaddr of 0. I've added a bunch of debug prints to the process; and for comparison also run it on QEMU emulating a Sabre board. On odroidc4 hardware: ## Starting application at 0x01080000 ... ELF-loader started on CPU: ARM Ltd. Cortex-A55 r1p0 paddr=[95e000..d5710f] No DTB passed in from boot loader. Looking for DTB in CPIO archive...found at a86de8. Loaded DTB from a86de8. paddr=[23f000..24afff] ELF-loading image 'kernel' to 0 paddr=[0..23efff] vaddr=[ffffff8000000000..ffffff800023efff] virt_entry=ffffff8000000000 ELF-loading image 'capdl-loader' to 24b000 paddr=[24b000..563fff] vaddr=[400000..718fff] virt_entry=408e48 Enabling MMU and paging Jumping to kernel-image entry point... Bootstrapping kernel Booting all finished, dropped to user space pre_init@serial.c:501 About to init port, io_ops=0x487cf0 ps_cdev_init@chardev.c:46 About to init_fn 3 ps_cdev_init@chardev.c:47 dev_defn[3].paddr: 0xff803000, size 1000 uart_init@serial.c:51 about to chardev_map: dev=0x473948, defn->id=3, defn->padd r=0xff803000 chardev_map@chardev.h:26 ops->io_mapper=0x487be0 &(ops->io_mapper)=0x442728 dev- >paddr=0xff803000 dev->size=0x1000 uart_init@serial.c:56 chardev_map mapped page_vaddr 0 plat_pre_init@plat.c:64 Failed to initialise character device plat_pre_init@plat.c:65 PS_SERIAL_DEFAULT: 3 On Sabre QEMU: ./simulate: qemu-system-arm -machine sabrelite -nographic -serial null -serial mon:stdio -m size=1024M -kernel images/capdl-loader-image- arm-imx6 ELF-loader started on CPU: ARM Ltd. Cortex-A9 r0p0 paddr=[106fc000..10aa98e3] No DTB passed in from boot loader. Looking for DTB in CPIO archive...found at 107fe33c. Loaded DTB from 107fe33c. paddr=[1003d000..10047fff] ELF-loading image 'kernel' to 10000000 paddr=[10000000..1003cfff] vaddr=[e0000000..e003cfff] virt_entry=e0000000 ELF-loading image 'capdl-loader' to 10048000 paddr=[10048000..10300fff] vaddr=[10000..2c8fff] virt_entry=187f8 Enabling MMU and paging Jumping to kernel-image entry point... Bootstrapping kernel Warning: Could not infer GIC interrupt target ID, assuming 0. Booting all finished, dropped to user space pre_init@serial.c:501 About to init port, io_ops=0x69cf0 ps_cdev_init@chardev.c:45 About to init_fn 1 ps_cdev_init@chardev.c:46 dev_defn[1].paddr: 0x21e8000, size 1000 uart_init@serial.c:224 about to chardev_map: dev=0x7f8c8, defn->id=1, defn->paddr=0x21e8000 chardev_map@chardev.h:26 ops->io_mapper=0x69cf0 &(ops->io_mapper)=0x1f328 dev->paddr=0x1f654 dev->size=0x4ebc4 uart_init@serial.c:226 chardev_map mapped vaddr 0xbb000 pollcli: Hello Serial Server! pollcli: abc This has me confused - it's good it works, but I can't follow in the flow how the paddr gets changed from the value supplied to chardev_map (ie 0x21e80000 becomes 0x1f654), yet in that case it works. Or is it a complication of using QEMU? A similar kind of test with AOS on odroidc4 - particularly the success of "*uart_init@uart.c:35 Mapped uart paddr:ff803000 size:1000 vaddr:b0000000*" ## Starting application at 0x01080000 ... ELF-loader started on CPU: ARM Ltd. Cortex-A55 r1p0 paddr=[88a000..c2b10f] No DTB passed in from boot loader. Looking for DTB in CPIO archive...found at 9f3068. Loaded DTB from 9f3068. paddr=[247000..252fff] ELF-loading image 'kernel' to 0 paddr=[0..246fff] vaddr=[ffffff8000000000..ffffff8000246fff] virt_entry=ffffff8000000000 ELF-loading image 'sos' to 253000 paddr=[253000..48cfff] vaddr=[400000..639fff] virt_entry=4172e0 Enabling MMU and paging Jumping to kernel-image entry point... Bootstrapping kernel Booting all finished, dropped to user space SOS Starting... <<seL4(CPU 0) [handleInterruptEntry/52 T0xffffff803fff8400 "SOS:root" @400630]: Spurious interrupt!>> <<seL4(CPU 0) [handleInterruptEntry/52 T0xffffff803fff8400 "SOS:root" @400630]: Spurious interrupt!>> <<seL4(CPU 0) [handleInterruptEntry/52 T0xffffff803fff8400 "SOS:root" @400630]: Spurious interrupt!>> <<seL4(CPU 0) [handleInterruptEntry/52 T0xffffff803fff8400 "SOS:root" @400630]: Spurious interrupt!>> <<seL4(CPU 0) [handleInterruptEntry/52 T0xffffff803fff8400 "SOS:root" @400630]: Spurious interrupt!>> <<seL4(CPU 0) [handleInterruptEntry/52 T0xffffff803fff8400 "SOS:root" @400630]: Spurious interrupt!>> <<seL4(CPU 0) [handleInterruptEntry/52 T0xffffff803fff8400 "SOS:root" @400630]: Spurious interrupt!>> uart_init@uart.c:35 Mapped uart paddr:ff803000 size:1000 vaddr:b0000000 SOS Started! test_cspace@tests.c:59 Test cspace run_tests@tests.c:174 Root CSpace test passed! test_cspace@tests.c:59 Test cspace run_tests@tests.c:182 Single level cspace test passed! test_cspace@tests.c:59 Test cspace cspace_alloc_slot@cspace.c:335 Cspace is full! run_tests@tests.c:195 Double level cspace test passed! run_tests@tests.c:199 DMA test passed! run_tests@tests.c:203 Frame table test passed! Network init dwmac.b0002000 Waiting for PHY auto negotiation to complete........ done Speed: 1000, full duplex Protocol ethernet registered (layer: 2). Protocol ipv4 registered (layer: 3). Protocol ipv6 registered (layer: 3). Protocol icmp4 registered (layer: 4). Protocol icmp6 registered (layer: 4). Protocol igmp registered (layer: 4). Protocol udp registered (layer: 4). Protocol tcp registered (layer: 4). Assigned ipv4 0.0.0.0 to device sos picotcp DHCP client: update link Assigned ipv4 192.168.200.125 to device sos picotcp DHCP client: renewal time (T1) 43200 DHCP client: rebinding time (T2) 75600 DHCP client: lease time 86400 DHCP client: netmask 255.255.255.0 DHCP client: gateway 192.168.200.4 Timer init Start first process Starting ttytest at 0x4001c8 SOS entering syscall loop aos: Error attempting syscall 29 task: Hello world, I'm tty_test! handle_syscall@main.c:128 Unknown syscall 1 <<seL4(CPU 0) [receiveIPC/148 T0xffffff803fff8400 "SOS:root" @407a48]: Reply obj ect already has unexecuted reply!>> In this case it has worked, sos_map_device works as expected (although the spurious interrupts are another task to figure out). But trying to understand what's really going on underneath ps_io_map and ultimately why libplatsupport won't work for me has got me confused. Any ideas would be appreciated. Regards Rob

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camkes-vm-linux kernel example
by Hugo V.C. 01 Jul '21

01 Jul '21

Hi, just a simple question: why this tutorial: https://docs.sel4.systems/Tutorials/camkes-vm-linux.html shows this output: Welcome to Buildroot buildroot login: root Password: # grep poke /proc/devices # figure out the major number of our driver 244 poke # mknod /dev/poke c 244 0 # create the special file # echo > /dev/poke # write to the file [ 57.389643] hi -sh: write error: Bad address # the shell complains, but our module is being invoked! I'm not getting the shell complain error, just this: # grep poke /proc/devices 247 poke # mknod /dev/poke c 247 0 # echo > /dev/poke [ 138.946905] TOC TOC NEO... # FYI: my kernel is a custom compiled one but same version as the pre-compiled you provide: # uname -a Linux buildroot 4.9.189 #4 SMP Thu Jun 24 00:16:49 CEST 2021 aarch64 GNU/Linux Any hint? Cheers,

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How will drivers work?
by Isaac Beckett 01 Jul '21

01 Jul '21

Hello! Operating system noob here, I understand that in most mainstream operating systems (Linux, BSDs, MacOS, Windows) drivers are part of the kernel. And in micro kernel operating systems like Minix and seL4, drivers are part of user space. But Minix is a lot closer to a traditional POSIX kernel, and seems to implement some of that (IE posix threads, IPC) in the kernel, which makes the environment for a driver programmer a bit more familiar. How do drivers work in seL4, then? How does a driver obtain permission for hardware access from the kernel? I imagine it works with a capability delegated by the root task, but how do you solve chicken and the egg type problems, like loading driver code, without driver code already loaded? Is it an initramfs like Linux/Unix? Also, what if seL4 is being used _as_ the firmware/bootloader? Obviously it can load the seL4 kernel and user space OS components from a file system to put them in the booting OS’ memory, but how does it load drivers for itself? I’m assuming there’s some low level platform specific code, but is that code verified or part of the proofs?

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Re: Tutorial Problem
by Peter Chubb 30 Jun '21

30 Jun '21

>>>>> "Michael" == Michael Neises <neisesmichael(a)gmail.com> writes: Michael> Peter, When I try to remove vme from the -cpu line, I get the Michael> following error at simulation time: OK, so you need nested virtualisation. That's not supported in code-translation mode, only when you're using the KVM kernel module. The message you got was about the simulated CPU, not your host. If you can enable KVM, qemu will pass through your host to the simulation. Looks like you have the kernel packages installed, now you need to make sure that: 1, The version of qemu you're using supports KVM, and 2. you have permissions to use KVM. The first is easy. On Debian-derived systems (debian, ubuntu, mint, etc) sudo apt install qemu-kvm should do the trick. Similarly sudo yum install qemu-kvm on Redhat-derived systems. The second is a little harder. Do ls -l /dev/kvm You'll see something like crw-rw----+ 1 root kvm 10, 232 Jun 30 09:13 /dev/kvm if kvm is installed. The second username (in this case, 'kvm') is the group you need to be in. Do sudo useradd your-login kvm (replacing 'kvm' with the actual group /dev/kvm is in, and 'your-login' with you local login name.) qemu-system-x86_84 -enable-kvm should then work. Peter C -- Dr Peter Chubb https://trustworthy.systems/ Trustworthy Systems Group CSE, UNSW

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Tutorial Problem
by Michael Neises 30 Jun '21

30 Jun '21

Hello everyone, The tutorials provided here are failing to build for me: https://github.com/seL4/sel4-tutorials Here are the steps to reproduce the errors: git clone git@github.com:seL4/seL4-CAmkES-L4v-dockerfiles.git && git clone git@github.com:seL4/sel4-tutorials.git && make -C ./seL4-CAmkES-L4v-dockerfiles user HOST_DIR=$(pwd)\ followed by cd sel4-tutorials && mkdir build && cd build && ../init.py --plat pc99 --tut camkes-vm-linux Then I am met with the error: ERROR:root:Parent directory is not tutorials root directory which I can fix by changing this line to read "init.py": https://github.com/seL4/sel4-tutorials/blob/d040028999b83c6af2309785f746810… Trying again after this edit, I meet the following errors: loading initial cache file ../projects/sel4-tutorials/settings.cmake CMake Error: Error processing file: ../projects/sel4-tutorials/settings.cmake CMake Error: The source directory "/host/sel4-tutorials/build" does not appear to contain CMakeLists.txt. Specify --help for usage, or press the help button on the CMake GUI. Traceback (most recent call last): File "../init.py", line 90, in <module> sys.exit(main()) File "../init.py", line 78, in main result = common.init_directories(args.plat, args.tut, args.solution, File "/host/sel4-tutorials/common.py", line 101, in init_directories return _init_build_directory(config, initialised, build_directory, tute_directory, output, config_dict=config_dict) File "/host/sel4-tutorials/common.py", line 69, in _init_build_directory return sh.cmake(args + [tute_directory], _cwd=directory, _out=output, _err=output) File "/usr/local/lib/python3.8/dist-packages/sh.py", line 1520, in __call__ return RunningCommand(cmd, call_args, stdin, stdout, stderr) File "/usr/local/lib/python3.8/dist-packages/sh.py", line 784, in __init__ self.wait() File "/usr/local/lib/python3.8/dist-packages/sh.py", line 841, in wait self.handle_command_exit_code(exit_code) File "/usr/local/lib/python3.8/dist-packages/sh.py", line 865, in handle_command_exit_code raise exc sh.ErrorReturnCode_1: RAN: /usr/bin/cmake -G Ninja -DTUT_BOARD=pc -DTUT_ARCH=x86_64 -DFORCE_IOMMU=ON -DTUTORIAL_DIR=build -C ../projects/sel4-tutorials/settings.cmake /host/sel4-tutorials/build STDOUT: STDERR: Either I'm missing something obvious or these instructions have fallen out of date. In any case I would be grateful for any advice. Best, Michael Neises

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How to avoid seL4 passing packets to Linux VM guest
by Hugo V.C. 24 Jun '21

24 Jun '21

Hi, I wonder how to have seL4 host not passing network frames to Linux VM guest. I mean, I would like to have seL4 dealing with TCP/IP and processing packets at the host level but then I want to use a custom communication channel with the Linux guest. So, the very first step would be to stop forwarding network frames to the guest. Any hint where I can start experimenting with this? Cheers,

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Some small details in kernel code and docs
by Mark Jones 24 Jun '21

24 Jun '21

Hi All, Here are a few minor details/questions about the kernel code & documentation. (I've confirmed that these are present in the new seL4-12.1.0 release.) 1) kernel/include/arch/x86/arch/32/mode/machine.h has the following definition (some code elided): static inline word_t FORCE_INLINE x86_read_fs_base_impl(void) { word_t base = 0; base &= ...; base &= ...; base &= ...; return base; } I'm pretty sure that the three &= operators here should be |= or else the result is always going to be zero. The same issue occurs in x86_read_gs_base_impl in the same file. Some follow-up questions: Can anyone say if this would have been detected if the PC99 (32-bit) platform had been verified? More generally, where can I find information about how ia32 segment registers are handled by the kernel? Why aren't they just stored/restored like other user-level registers on kernel entry/exit? Is there something that prevents user-level changes in the ES register, for example, from being observed in other threads? 2) A CNodeRotate will generate a FailedLookup error if the pivot slot either doesn't exist or contains a null capability. But, in the first case the "lookup failed for a source capability" field in the error message is 1, while in the second it is 0. Hardly a serious problem, but this does seem inconsistent. Is this intentional, or a mistake in the specification that has been carried over to the implementation? 3) Section "3.4 Lookup Failure Description" of the manual describes how capability lookup errors are represented in an IPC buffer. But it seems the layout information is incorrect. For example, Section 3.4.2 says that "Offset + 0" will contain seL4_MissingCapability while the number of bits left will be at "Offset + seL4_CapFault_BitsLeft", which is probably supposed to be equivalent to "Offset + 1". But, based on kernel/libsel4/include/sel4/shared_types.h, it would seem that this gives "Offset + 4". Sections 3.4.3 and 3.4.4 have similar problems. 4) On https://docs.sel4.systems/GettingStarted, in the section labeled "Fetching, Configuring and Building seL4test", there are missing line breaks between the commands in the text boxes for Steps 1 and 2, and there are some tags in the text box for Step 4 that probably should not be displayed. Best wishes, and thanks for any feedback! Mark

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CAmkES ARM VM: SATA Passthrough
by Olof Holmberg 21 Jun '21

21 Jun '21

Hi, I ran into the issue of not being able to fit the whole rootfs in RAM (using a qemu-arm-virt device). Therefore I opted for booting the initramfs instead and from there switch root to the proper file system. The booting of the initramfs works fine but the /dev/sda device is not visible to the guest. For x86 (according to these instructions: https://docs.sel4.systems/projects/camkes-vm/) this seems to be done by passing through access to the SATA controller. But since the x86 device configuration is different to the ARM device configuration it requires a different config than the one shown in the instructions. I was wondering how you achieve this SATA passthrough for a ARM VM or if there are any tutorials, other projects or examples that shows how it is done? Best regards, Olof

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