April 2020 - Devel - lists.sel4.systems

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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Trouble accessing linux guest through tun/tap
by Travis Wheatley 22 May '20

22 May '20

Greetings, I am working with the camkes-arm-vm qemu-arm-virt configuration. I started with the vm_minimal configuration and have added a tun/tap interface by creating the tap on my host thusly: # ip tuntap add tap0 mode tap # ip addr add 10.0.120.100/24 dev tap0 # ip link set dev tap0 up I have added support for what I beleive to be the appropriate interrupts by modifying my devices.camkes file thusly: vm0.untyped_mmios = [ "0x8040000:12", // Interrupt Controller Virtual CPU interface (Virtual Machine view) "0x10040000:17", // QEMU PCI MMIO "0x3eff0000:16", // QEMU PCI IO ports "0x40000000:29", // Linux kernel memory regions ]; vm0.dtb_irqs = [35, 36, 37, 38]; Additionally, I have modified the settings.camkes thusly: if(${PLATFORM} STREQUAL "qemu-arm-virt") # force cpu set(QEMU_MEMORY "2048") set(KernelArmCPU cortex-a53 CACHE STRING "" FORCE) set(VmInitRdFile ON CACHE BOOL "" FORCE) set(VmPCISupport ON CACHE BOOL "" FORCE) set(VmVirtioNetArping OFF CACHE BOOL "" FORCE) set(VmVirtioNetVirtqueue ON CACHE BOOL "" FORCE) # set(qemu_sim_extra_args "-netdev tap,id=mynet0,ifname=tap0,script=no,downscript=no -device virtio-net,netdev=mynet0,mac=52:55:00:d1:55:01") set(qemu_sim_extra_args "-net nic,model=e1000 -netdev tap,id=mynet0,script=no,ifname=tap0 -device virtio-net,netdev=mynet0,mac=52:55:00:d1:55:01") set(KernelArmExportPCNTUser ON CACHE BOOL "" FORCE) set(KernelArmExportPTMRUser ON CACHE BOOL "" FORCE) endif() This results in a tunl0 interface showing up on my linux guest. However, that interface does not have a mac address associated with it. I can use ifconfig to assign an IP address on the same subnet as the corresponding tap interface on the host. However, I can’t ping between the two. I thought this might be because I have VmVitruoNetArping set to OFF. However, I get compile time errors when I turn it on. Because the tunl0 inteface does not have the mac address specied in the qemu_sim_extra_args I am unsure of how to set up an arp table entry. Exctly what do I need to do to enable network communications between my linux guest and the host?

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additional: some question about VisualCAmkES ？
by yadong.li 27 Apr '20

27 Apr '20

Hi， I found the VisualCAmkES tool can not parse grammar like import and marco in cmakes file, If I write very simple camkes file, only include one assembly and component. I want to know How can I use this VisualCAmkES tool to generate visual file in complex project like vm_minimal ? 发件人: yadong.li 发送时间: 2020年4月25日 21:06 收件人: 'devel(a)sel4.systems' 主题: some question about VisualCAmkES ？ Hi， I want to use VisualCAmkES for view，I follow the step of https://docs.sel4.systems/projects/camkes/visual-camkes/ I meet the below Problem， how can I resolve it ？ Thank you very much Syntax Error (u'/home/yadong.li/seL4_vm_11/ sel4_horizon/camkes-arm-vm/projects/vm/ apps/vm_cross_connector/vm_cross_connector.camkes:36:5: \x1b[31m\ x1b[1mVM_INIT_DEF\x1b[0m()', u' ', u"Syntax error in input at 'VM_INIT_DEF' (type ID) line 36 col 5", u"Syntax error in input at 'VM_GENERAL_COMPOSITION_DEF' (type ID) line 45 col 9", u"Syntax error in input at '(' (type _ANON_4) line 60 col 37")

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some question about VisualCAmkES ？
by yadong.li 25 Apr '20

25 Apr '20

Hi， I want to use VisualCAmkES for view，I follow the step of https://docs.sel4.systems/projects/camkes/visual-camkes/ I meet the below Problem， how can I resolve it ？ Thank you very much Syntax Error (u'/home/yadong.li/seL4_vm_11/ sel4_horizon/camkes-arm-vm/projects/vm/ apps/vm_cross_connector/vm_cross_connector.camkes:36:5: \x1b[31m\ x1b[1mVM_INIT_DEF\x1b[0m()', u' ', u"Syntax error in input at 'VM_INIT_DEF' (type ID) line 36 col 5", u"Syntax error in input at 'VM_GENERAL_COMPOSITION_DEF' (type ID) line 45 col 9", u"Syntax error in input at '(' (type _ANON_4) line 60 col 37")

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Re: [seL4] Trouble with the tun/tap interface in linux guest
by Travis Wheatley 23 Apr '20

23 Apr '20

Thank you for your reply Kent. I modified the devices.camkes in the corresponding project folder as suggested. However, I am still seeing the same behavior. Are there other items I need to add or is there something in the kernel that needs to be enabled? I tried swapping in an Ubuntu server 18.01 kernel. It boots, but I do not even see the tunl0 interface that I see when I boot the default vm_minimal image. Here is what the vm0.untyped_mmios block looks like in my devices.camakes file looks like vm0.untyped_mmios = [ "0x8040000:12", // Interrupt Controller Virtual CPU interface (Virtual Machine view) "0x10040000:17", // QEMU PCI MMIO "0x3eff0000:16", // QEMU PCI IO ports "0x40000000:29", // Linux kernel memory regions ]; vm0.dtb_irqs = [35, 36, 37, 38]; I found that the vm_multi project devices.camkes has similar stanzas in the vm0.untyped.mmios block. However, the Interrupt controller item has an additional 0x1000 token in it: "0x8040000:0x1000:12", // Interrupt Controller Virtual CPU interface (Virtual Machine view) I tried this in the vm_minimal configurationo but ../init.sh throws an error indicating that it doesn’t know how to parse that. I also was able to boot the vm_multi configuration in the emulator and noticed that it did, in fact, have both an eth0 and eth1 interface, but was not able to get them to work because the kernel seemed to be stuck in a loop looking for a non-existent DHCP server. Wondering if there is some other config somewhere that I need to get a working eth0 interface on the vm_minimal configuration? Message: 1 Date: Tue, 21 Apr 2020 20:57:24 +0000 From: Travis Wheatley <travis.wheatley(a)emergentspace.com<mailto:travis.wheatley@emergentspace.com>> To: "devel(a)sel4.systems<mailto:devel@sel4.systems>" <devel(a)sel4.systems<mailto:devel@sel4.systems>> Subject: [seL4] Trouble with the tun/tap interface in linux guest Message-ID: <207FF441-86A1-4CE3-88AD-8BACC908138D(a)emergentspace.com<mailto:207FF441-86A1-4CE3-88AD-8BACC908138D@emergentspace.com>> Content-Type: text/plain; charset="utf-8" Thanks to recent patches I have been able to build and boot the linux guest kernel under the simulator in the camkes-arm-vm project using the vm_minimal configuration. However, I am having trouble accessing it via the network interface. First I set up a tap interface as follows: # sudo ip tuntap add tap0 mode tap # sudo ip addr add 10.0.120.100/24 dev tap0 # sudo ip link set dev tap0 up Then I start the simulation using the following command line, which I believe should make the tap interface appear as an e1000 nic to the guest kernel: ./simulate --extra-qemu-args="-net nic,model=e1000 -net tap,script=no,ifname=tap0? In the linux guest the ?ip a? command shows that there is a tunl0 network device available. I have tried a couple of methods of activating it including using ifconfig to bring it up and assign it an ip address as well as the ?ip link set tun0 up? followed by the ?ip addr add 10.0.120.1/24 dev tunl0? command. According to ifconfig both of these bring the interface up and provide it with an ip address. However, I can?t ping the tap ip address from the guest nor can I ping the guest tunl0 interface from another console on the host. So, what am I missing? ------------------------------ Message: 2 Date: Tue, 21 Apr 2020 23:09:16 +0000 From: "Mcleod, Kent (Data61, Kensington NSW)" <Re: [seL4] Trouble with the tun/tap interface in linux guest> To: Travis Wheatley <travis.wheatley(a)emergentspace.com<mailto:travis.wheatley@emergentspace.com>>, "devel(a)sel4.systems<mailto:devel@sel4.systems>" <devel(a)sel4.systems<mailto:devel@sel4.systems>> Subject: Re: [seL4] Trouble with the tun/tap interface in linux guest Message-ID: <SYXPR01MB0832783D9CD6B3B03B0F04FFABD50(a)SYXPR01MB0832.ausprd01.prod.outlook.com<mailto:SYXPR01MB0832783D9CD6B3B03B0F04FFABD50@SYXPR01MB0832.ausprd01.prod.outlook.com>> Content-Type: text/plain; charset="iso-8859-1" It could be that the camkes configuration doesn't pass through the PCI device to the Linux guest? You need to add the Interrupts and PCI MMIO configurations below: ? ? ? ? vm0.untyped_mmios = [ ? ? ? ? ? ? ? ? ? ? "0x8040000:12", // Interrupt Controller Virtual CPU interface (Virtual Machine view) ? ? ? ? ? ? ? ? ? ? "0x10040000:17", // QEMU PCI MMIO ? ? ? ? ? ? ? ? ? ? "0x3eff0000:16", // QEMU PCI IO ports ? ? ? ? ? ? ? ? ? ? "0x40000000:29", // Linux kernel memory regions ? ? ? ? ? ? ? ? ? ? ]; ? ? ? ? vm0.dtb_irqs = ?[35, 36, 37, 38]; The device should then appear in the guest under eth0. Kent. ------------------------------ Subject: Digest Footer _______________________________________________ Devel mailing list Devel(a)sel4.systems<mailto:Devel@sel4.systems> https://sel4.systems/lists/listinfo/devel ------------------------------ End of Devel Digest, Vol 71, Issue 24 *************************************

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Trouble with the tun/tap interface in linux guest
by Travis Wheatley 22 Apr '20

22 Apr '20

Thanks to recent patches I have been able to build and boot the linux guest kernel under the simulator in the camkes-arm-vm project using the vm_minimal configuration. However, I am having trouble accessing it via the network interface. First I set up a tap interface as follows: # sudo ip tuntap add tap0 mode tap # sudo ip addr add 10.0.120.100/24 dev tap0 # sudo ip link set dev tap0 up Then I start the simulation using the following command line, which I believe should make the tap interface appear as an e1000 nic to the guest kernel: ./simulate --extra-qemu-args="-net nic,model=e1000 -net tap,script=no,ifname=tap0” In the linux guest the “ip a” command shows that there is a tunl0 network device available. I have tried a couple of methods of activating it including using ifconfig to bring it up and assign it an ip address as well as the “ip link set tun0 up” followed by the “ip addr add 10.0.120.1/24 dev tunl0” command. According to ifconfig both of these bring the interface up and provide it with an ip address. However, I can’t ping the tap ip address from the guest nor can I ping the guest tunl0 interface from another console on the host. So, what am I missing?

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Incorporating the Build System - The CAmkES Perspective
by Turner, Ben 21 Apr '20

21 Apr '20

Hi, We are attempting to define a system that comprises 3 components that can talk to each other. We have managed to get the system built and working using the existing tutorial repo and the hello-camkes-0 app, however we are struggling to determine what precisely we would need to copy from this in order to define our own standalone application within the seL4 build system. We have read the existing documentation at https://docs.sel4.systems/projects/buildsystem/incorporating.html but cannot find any information on what additions are required when using the CAmkES and ARM capabilities. Any help you can provide would be appreciated. Kind regards, Ben Turner ________________________________________ Roke Manor Research Limited, Romsey, Hampshire, SO51 0ZN, United Kingdom.Part of the Chemring Group. Registered in England & Wales. Registered No: 00267550 http://www.roke.co.uk _______________________________________ The information contained in this e-mail and any attachments is proprietary to Roke Manor Research Limited and must not be passed to any third party without permission. This communication is for information only and shall not create or change any contractual relationship. ________________________________________

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TimeServer "IRQ already mapped" error
by Grant Jurgensen 17 Apr '20

17 Apr '20

Hi all, I'm trying to add a timer to my CAmkES component (all I need is a timestamp). I've been using this example component as a reference: https://github.com/seL4/camkes/tree/master/apps/timeserver My problem is that when I declare an instance of the global TimeServer component in my ".camkes" file, I get an error at build-time: "parse-capDL: IRQ already mapped: 68". I'm not sure what to make of this error. The only major difference between my project and the reference above is that I am building atop the camkes-arm-vm project. Could the VM be interfering here? Thanks, Grant Jurgensen

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Benchmarks of seL4
by Leo Gaspard 16 Apr '20

16 Apr '20

Hello, I come wondering: the FAQ claims that seL4 is “the world's fastest microkernel”. However, I can only find benchmarks of just seL4, without comparison to other operating systems running on the same machine. Would you happen to have such comparative benchmarks? I'd be particularly interested by something against L4Re, as it'd probably allow me to guess at the performance of something similar to L4Linux ported to seL4. Thank you for all you do on seL4! Leo

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Failed to find device frame in new verion on my environment
by yadong.li 16 Apr '20

16 Apr '20

Hi， I recently move my wrok to a new seL4 version (I checkout default.xml in project camkes-arm-vm on 2020.02.25), I have below error print: “create_object@main.c:659 [Cond failed: err != seL4_NoError] Failed to find device frame/untyped at paddr = 0x90006000” 1、 I debug code, /**/ is my environment run parameter BOOT_CODE bool_t create_device_untypeds(cap_t root_cnode_cap, seL4_SlotPos slot_pos_before) { paddr_t start = 0; /*---------------------add region, start = 0x1800000, end = 0x2080000 *---------------------add region, start = 0x20ff000, end = 0x2100000 *---------------------add region, start = 0x80000000, end = 0x90001000 *---------------------add region, start = 0x90003000, end = 0x90004000 */ for (word_t i = 0; i < ndks_boot.resv_count; i++) { if (start < ndks_boot.reserved[i].start) { region_t reg = paddr_to_pptr_reg((p_region_t) { start, ndks_boot.reserved[i].start }); if (!create_untypeds_for_region(root_cnode_cap, true, reg, slot_pos_before)) { return false; } } start = ndks_boot.reserved[i].end; } /*---------------------add region, start = 0x90005000, CONFIG_PADDR_USER_DEVICE_TOP = 0xff, PPTR_TOP = 0xffffc0000000*/ if (start < CONFIG_PADDR_USER_DEVICE_TOP) { region_t reg = paddr_to_pptr_reg((p_region_t) { start, CONFIG_PADDR_USER_DEVICE_TOP }); /* * The auto-generated bitfield code will get upset if the * end pptr is larger than the maximum pointer size for this architecture. */ if (reg.end > PPTR_TOP) { reg.end = PPTR_TOP; } if (!create_untypeds_for_region(root_cnode_cap, true, reg, slot_pos_before)) { return false; } } return true; } 2、 CONFIG_PADDR_USER_DEVICE_TOP = 0xff, I found print the value must use 0x%x, can’t use 0x%lx, it is wrong 3、My platform is cortexA53 kernel/src/plat/j2/config.cmake:28: set(KernelArmCortexA53 ON) 4、and I change follow KernelArmCortexA53： a) ‘math(EXPR KernelPaddrUserTop "(1 << 40) - 1")’ to ‘set(KernelPaddrUserTop "1099511627775")’ ----------the print is “Failed to find device frame” disappear 5、my pc tools install，follow the seL4 wiki， cmakes version is 3.12.2 (> 3.7.2) 6、I did not find error or warning when I ../init-build.sh -DAARCH64=TRUE …… ---------------is it need to install new tools? Or other problem Thank you very much.

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