Devel April 2019

devel@sel4.systems

5 participants
5 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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TLB issue
by Stefan Kalkowski 15 Nov '19

15 Nov '19

Dear sel4 community, yesterday I've started to develop a low-level platform test to stress several multi-processor aspects on top of the Genode API. Thereby, I've recognized that on sel4/x86_64 the TLB is practically not always cleaned properly in SMP systems. The test spawns threads of one protection domain on each available cpu. Each thread accesses one of the first words of a shared dataspace. Afterwards the main thread on CPU 0 detaches and destroys the dataspace. Unfortunately, the threads on other CPUs still successfully access the corresponding memory instead of triggering a fault. To be able to reproduce the problem, you might investigate the simple test case here: https://github.com/skalk/genode/commit/2d2d7f982555f551227ad5dcbf9df46705d7… My colleague Alexander Boettcher already investigated the problem in part, and might share his insights with you. Best regards Stefan -- Stefan Kalkowski Genode labs https://github.com.skalk | https://genode.org

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Sel4 for quadcore riscv64imafd
by Sreenadh S 03 Oct '19

03 Oct '19

I want to build sel4 for quadcore riscv64imafd and run the test programs, how to do that? Regards, Sreenadh S, CDAC, Trivandrum, India

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Undefined Reference iommu dma
by KAP Benjamin 26 Apr '19

26 Apr '19

Hello I have a linking problem in the picoserver CAmkES-application which was added 2 days ago. Steps I did: 1) repo init -u https://github.com/seL4/camkes-manifest.git 2) repo sync 3) start docker container 4) (in new subfolder) ../init-build.sh -DPLATFORM=x86_64 -DSIMULATION=1 -DCAMKES_APP=picoserver (side note: aborts because picotcp folder is missing in projects folder, but that's easy fixed) 5) ninja Error: [5/16] Linking C executable projects/camkes/ethdriver.instance.bin FAILED: projects/camkes/ethdriver.instance.bin : && ccache /usr/bin/gcc --sysroot=/host/test -m64 -march=nehalem -D__KERNEL_64__ -g -march=nehalem -D__KERNEL_64__ -Wl,-m -Wl,elf_x86_64 -static -nostdlib -z max-page-size=0x1000 -static -nostdlib -u _camkes_start -e _camkes_start -Wl,--script=/host/test/projects/camkes/ethdriver/linker.lds /host/test/lib/crt1.o /host/test/lib/crti.o /usr/lib/gcc/x86_64-linux-gnu/6/crtbegin.o projects/camkes/CMakeFiles/ethdriver.instance.bin.dir/__/global-components/components/Ethdriver/src/ethdriver.c.obj projects/camkes/CMakeFiles/ethdriver.instance.bin.dir/__/global-components/components/Ethdriver/src/plat/pc99/common.c.obj projects/camkes/CMakeFiles/ethdriver.instance.bin.dir/__/global-components/components/Ethdriver/src/plat/pc99/82574.c.obj projects/camkes/CMakeFiles/ethdriver.instance.bin.dir/ethdriver/camkes.c.obj projects/camkes/CMakeFiles/ethdriver.instance.bin.dir/ethdriver/camkes.simple.c.obj projects/camkes/CMakeFiles/ethdriver.instance.bin.dir/ethdriver/camkes.environment.c.obj projects/camkes/CMakeFiles/ethdriver.instance.bin.dir/ethdriver/EthDriver_seL4HardwareMMIO_0.c.obj projects/camkes/CMakeFiles/ethdriver.instance.bin.dir/ethdriver/irq_seL4HardwareInterrupt_0.c.obj projects/camkes/CMakeFiles/ethdriver.instance.bin.dir/ethdriver/client_seL4Ethdriver_0.c.obj -lgcc -lgcc_eh libsel4/libsel4.a projects/camkes-tool/libsel4camkes/libsel4camkes.a projects/seL4_libs/libsel4sync/libsel4sync.a projects/util_libs/libutils/libutils.a projects/seL4_libs/libsel4vka/libsel4vka.a projects/seL4_libs/libsel4utils/libsel4utils.a projects/seL4_libs/libsel4platsupport/libsel4platsupport.a projects/util_libs/libplatsupport/libplatsupport.a projects/seL4_libs/libsel4vspace/libsel4vspace.a projects/seL4_libs/libsel4muslcsys/libsel4muslcsys.a projects/seL4_libs/libsel4utils/libsel4utils.a projects/seL4_libs/libsel4vka/libsel4vka.a projects/seL4_libs/libsel4allocman/libsel4allocman.a projects/seL4_libs/libsel4vspace/libsel4vspace.a projects/seL4_libs/libsel4simple/libsel4simple.a projects/seL4_libs/libsel4platsupport/libsel4platsupport.a projects/util_libs/libethdrivers/libethdrivers.a projects/projects_libs/libvirtqueue/libvirtqueue.a projects/seL4_libs/libsel4utils/libsel4utils.a projects/seL4_libs/libsel4platsupport/libsel4platsupport.a projects/seL4_libs/libsel4simple-default/libsel4simple-default.a projects/seL4_libs/libsel4debug/libsel4debug.a projects/seL4_libs/libsel4simple/libsel4simple.a projects/util_libs/libelf/libelf.a projects/util_libs/libcpio/libcpio.a projects/seL4_libs/libsel4vspace/libsel4vspace.a projects/seL4_libs/libsel4vka/libsel4vka.a libsel4/libsel4.a projects/util_libs/libplatsupport/libplatsupport.a projects/util_libs/libutils/libutils.a projects/musllibc/build-temp/lib/libc.a projects/util_libs/libpicotcp/picotcp_external/picotcp/build//lib/libpicotcp.a -lgcc -lgcc_eh libsel4/libsel4.a projects/camkes-tool/libsel4camkes/libsel4camkes.a projects/seL4_libs/libsel4sync/libsel4sync.a projects/util_libs/libutils/libutils.a projects/seL4_libs/libsel4vka/libsel4vka.a projects/seL4_libs/libsel4utils/libsel4utils.a projects/seL4_libs/libsel4platsupport/libsel4platsupport.a projects/util_libs/libplatsupport/libplatsupport.a projects/seL4_libs/libsel4vspace/libsel4vspace.a projects/seL4_libs/libsel4muslcsys/libsel4muslcsys.a projects/seL4_libs/libsel4utils/libsel4utils.a projects/seL4_libs/libsel4vka/libsel4vka.a projects/seL4_libs/libsel4allocman/libsel4allocman.a projects/seL4_libs/libsel4vspace/libsel4vspace.a projects/seL4_libs/libsel4simple/libsel4simple.a projects/seL4_libs/libsel4platsupport/libsel4platsupport.a projects/util_libs/libethdrivers/libethdrivers.a projects/projects_libs/libvirtqueue/libvirtqueue.a projects/seL4_libs/libsel4utils/libsel4utils.a projects/seL4_libs/libsel4platsupport/libsel4platsupport.a projects/seL4_libs/libsel4simple-default/libsel4simple-default.a projects/seL4_libs/libsel4debug/libsel4debug.a projects/seL4_libs/libsel4simple/libsel4simple.a projects/util_libs/libelf/libelf.a projects/util_libs/libcpio/libcpio.a projects/seL4_libs/libsel4vspace/libsel4vspace.a projects/seL4_libs/libsel4vka/libsel4vka.a libsel4/libsel4.a projects/util_libs/libplatsupport/libplatsupport.a projects/util_libs/libutils/libutils.a projects/musllibc/build-temp/lib/libc.a projects/util_libs/libpicotcp/picotcp_external/picotcp/build//lib/libpicotcp.a /usr/lib/gcc/x86_64-linux-gnu/6/crtend.o /host/test/lib/crtn.o -o projects/camkes/ethdriver.instance.bin && : /usr/bin/ld: projects/camkes/CMakeFiles/ethdriver.instance.bin.dir/__/global-components/components/Ethdriver/src/plat/pc99/common.c.obj: in function `camkes_iommu_dma_alloc': /host/test/../projects/global-components/components/Ethdriver/src/plat/pc99/common.c:48: undefined reference to `sel4utils_iommu_dma_alloc_iospace' /usr/bin/ld: projects/camkes/CMakeFiles/ethdriver.instance.bin.dir/__/global-components/components/Ethdriver/src/plat/pc99/common.c.obj: in function `pc99_eth_setup': /host/test/../projects/global-components/components/Ethdriver/src/plat/pc99/common.c:71: undefined reference to `simple_get_iospace' /usr/bin/ld: /host/test/../projects/global-components/components/Ethdriver/src/plat/pc99/common.c:88: undefined reference to `sel4utils_make_iommu_dma_alloc' I checked all the files in the Ethdriver component and for me it seems that all should be fine, thus I cannot find/see the error (or the missing configuration). (The only file I edited was picoserver.camkes but that is irrelevant.) Any help/hint would be very appreciated. Best regards, Benjamin

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seL4 process memory utilization
by Leonid Meyerovich 26 Apr '19

26 Apr '19

Hello, Is there any way in seL4 (library function?) to check free heap memory? Thank you, Leonid ________________________________ This message and all attachments are PRIVATE, and contain information that is PROPRIETARY to Intelligent Automation, Inc. You are not authorized to transmit or otherwise disclose this message or any attachments to any third party whatsoever without the express written consent of Intelligent Automation, Inc. If you received this message in error or you are not willing to view this message or any attachments on a confidential basis, please immediately delete this email and any attachments and notify Intelligent Automation, Inc.

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