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Refactor VM setup page
Signed-off-by: Sergiu Weisz <sergiu121@gmail.com>
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‎Documentation/teaching/info/extra-vm.rst

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=====================================
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Customizing the Virtual Machine Setup
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=====================================
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Connect to the Virtual Machine via SSH
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--------------------------------------
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The default Yocto image for the QEMU virtual machine
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(``core-image-minimal-qemu``) provides the minimal functionality to run the
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kernel and kernel modules. For extra features, such as an SSH connection,
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a more complete image is required, such as ``core-image-sato-dev-qemu``.
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To use the new image, update the ``YOCTO_IMAGE`` variable in
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``tools/labs/qemu/Makefile``:
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.. code-block::
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YOCTO_IMAGE = core-image-sato-qemu$(ARCH).ext4
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When you start the virtual machine the first time using ``make boot`` with the
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new image configuration, it will download the image and then boot the virtual
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machine. The image is larger (around 400MB) than the minimal image so expect
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some time for the download.
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You then enter the virtual machine via ``minicom``, determine the IP address of
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the ``eth0`` interface an then you can connect to the virtual machine via SSH:
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.. code-block:: shell
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$ minicom -D serial.pts
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Poky (Yocto Project Reference Distro) 2.3 qemux86 /dev/hvc0
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qemux86 login: root
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root@qemux86:~# ip a s
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1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue qlen 1000
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link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
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inet 127.0.0.1/8 scope host lo
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valid_lft forever preferred_lft forever
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inet6 ::1/128 scope host
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valid_lft forever preferred_lft forever
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2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast qlen 1000
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link/ether 52:54:00:12:34:56 brd ff:ff:ff:ff:ff:ff
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inet 172.213.0.18/24 brd 172.213.0.255 scope global eth0
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valid_lft forever preferred_lft forever
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inet6 fe80::5054:ff:fe12:3456/64 scope link
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valid_lft forever preferred_lft forever
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3: sit0@NONE: <NOARP> mtu 1480 qdisc noop qlen 1000
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link/sit 0.0.0.0 brd 0.0.0.0
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$ ssh -l root 172.213.0.18
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The authenticity of host '172.213.0.18 (172.213.0.18)' can't be established.
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RSA key fingerprint is SHA256:JUWUcD7LdvURNcamoPePMhqEjFFtUNLAqO+TtzUiv5k.
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Are you sure you want to continue connecting (yes/no)? yes
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Warning: Permanently added '172.213.0.18' (RSA) to the list of known hosts.
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root@qemux86:~# uname -a
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Linux qemux86 4.19.0+ #3 SMP Sat Apr 4 22:45:18 EEST 2020 i686 GNU/Linux
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Connecting a Debugger to the Virtual Machine Kernel
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---------------------------------------------------
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You can use GDB to connect to the running virtual machine kernel and inspect
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the state of the kernel. You run ``make gdb`` in ``tools/labs/``:
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.. code-block:: shell
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.../linux/tools/labs$ make gdb
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ln -fs /home/tavi/src/linux/vmlinux vmlinux
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gdb -ex "target remote localhost:1234" vmlinux
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GNU gdb (Ubuntu 7.11.1-0ubuntu1~16.04) 7.11.1
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Copyright (C) 2016 Free Software Foundation, Inc.
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License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
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This is free software: you are free to change and redistribute it.
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There is NO WARRANTY, to the extent permitted by law. Type "show copying"
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and "show warranty" for details.
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This GDB was configured as "x86_64-linux-gnu".
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Type "show configuration" for configuration details.
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For bug reporting instructions, please see:
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<http://www.gnu.org/software/gdb/bugs/>.
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Find the GDB manual and other documentation resources online at:
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<http://www.gnu.org/software/gdb/documentation/>.
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For help, type "help".
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Type "apropos word" to search for commands related to "word"...
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Reading symbols from vmlinux...done.
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Remote debugging using localhost:1234
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0xc13cf2f2 in native_safe_halt () at ./arch/x86/include/asm/irqflags.h:53
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53asm volatile("sti; hlt": : :"memory");
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(gdb) bt
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#0 0xc13cf2f2 in native_safe_halt () at ./arch/x86/include/asm/irqflags.h:53
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#1 arch_safe_halt () at ./arch/x86/include/asm/irqflags.h:95
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#2 default_idle () at arch/x86/kernel/process.c:341
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#3 0xc101f136 in arch_cpu_idle () at arch/x86/kernel/process.c:332
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#4 0xc106a6dd in cpuidle_idle_call () at kernel/sched/idle.c:156
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#5 do_idle () at kernel/sched/idle.c:245
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#6 0xc106a8c5 in cpu_startup_entry (state=<optimized out>)
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at kernel/sched/idle.c:350
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#7 0xc13cb14a in rest_init () at init/main.c:415
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#8 0xc1507a7a in start_kernel () at init/main.c:679
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#9 0xc10001da in startup_32_smp () at arch/x86/kernel/head_32.S:368
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#10 0x00000000 in ?? ()
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(gdb)
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Rebuild the Kernel Image
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------------------------
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The kernel image is built the first time the VM is started. To rebuild the
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kernel remove the kernel image file defined by the ``ZIMAGE`` variable in
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``tools/labs/qemu/Makefile``:
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.. code-block::
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ZIMAGE = $(KDIR)/arch/$(ARCH)/boot/$(b)zImage
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Typically the full path of the kernel is ``arch/x86/boot/bzImage``.
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Once removed the kernel image is rebuild by using:
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.. code-block:: shell
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~/src/linux/tools/labs$ make zImage
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or simply starting the virtual machine
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.. code-block:: shell
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~/src/linux/tools/labs$ make boot

‎Documentation/teaching/info/vm.rst

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Virtual Machine Setup
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=====================
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Exercises are designed to run on a qemu based virtual machine. In
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order to run the virtual machine you will need following packages:
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Practice work is designed to run on a QEMU based virtual machine. Kernel code
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is developed and built on the host machine and then deployed and run on the
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virtual machine.
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* build-essential
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* qemu-system-x86
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* qemu-system-arm
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* kvm
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* python3
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In order to run and use the virtual machine the following packages are required
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on a Debian/Ubuntu system:
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The virtual machine setup uses prebuild Yocto images that it downloads
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from downloads.yocyoproject.org and a kernel image that it builds
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itself. The following images are supported:
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* ``build-essential``
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* ``gcc-multilib``
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* ``libncurses5-dev``
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* ``qemu-system-x86``
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* ``qemu-system-arm``
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* ``kvm``
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* ``python3``
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* ``minicom``
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* core-image-minimal-qemu
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* core-image-minimal-dev-qemu
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* core-image-sato-dev-qemu
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* core-image-sato-qemu
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* core-image-sato-sdk-qemu
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The virtual machine setup uses prebuild Yocto images that it downloads and a
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kernel image that it builds itself. The following images are supported:
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and can be selected from tools/labs/qemu/Makefile.
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* ``core-image-minimal-qemu``
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* ``core-image-minimal-dev-qemu``
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* ``core-image-sato-dev-qemu``
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* ``core-image-sato-qemu``
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* ``core-image-sato-sdk-qemu``
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By default, ``core-image-minimal-qemu`` it used. This setting can be changed by
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updating the ``YOCTO_IMAGE`` variable in ``tools/labs/qemu/Makefile``.
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Starting the VM
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---------------
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Starting the Virtual Machine
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----------------------------
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The virtual machine scripts are available in tools/labs/qemeu and you
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can can start the virtual machine by using the **boot** make target in
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tools/labs:
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You start the virtual machine in the ``tools/labs/`` folder by running ``make
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boot``:
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.. code-block:: shell
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~/src/linux/tools/labs$ make boot
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ARCH=x86 qemu/qemu.sh -kernel zImage.x86 -device virtio-serial \
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-chardev pty,id=virtiocon0 -device virtconsole,chardev=virtiocon0 \
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-net nic,model=virtio,vlan=0 -net tap,ifname=tap0,vlan=0,script=no,downscript=no\
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-drive file=rootfs.img,if=virtio,format=raw --append "root=/dev/vda console=hvc0" \
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--display none -s
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char device redirected to /dev/pts/19 (label virtiocon0)
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.../linux/tools/labs$ make boot
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The first run of the ``make boot`` command will compile the kernel image and it
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will take longer. Subsequent runs will only start the QEMU virtual machine,
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with verbose output provided:
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.. note:: To show the qemu console use "QEMU_DISPLAY=gtk make
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boot". This will show the VGA output and will also give
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access to the standard keyboard.
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.. code-block:: shell
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.. _vm_interaction_link:
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.../linux/tools/labs$ make boot
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mkdir /tmp/tmp.7rWv63E9Wf
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sudo mount -t ext4 -o loop core-image-minimal-qemux86.ext4 /tmp/tmp.7rWv63E9Wf
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sudo make -C /home/razvan/school/so2/linux.git modules_install INSTALL_MOD_PATH=/tmp/tmp.7rWv63E9Wf
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make: Entering directory '/home/razvan/school/so2/linux.git'
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INSTALL crypto/crypto_engine.ko
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INSTALL drivers/crypto/virtio/virtio_crypto.ko
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INSTALL drivers/net/netconsole.ko
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DEPMOD 4.19.0+
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make: Leaving directory '/home/razvan/school/so2/linux.git'
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sudo umount /tmp/tmp.7rWv63E9Wf
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rmdir /tmp/tmp.7rWv63E9Wf
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sleep 1 && touch .modinst
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qemu/create_net.sh tap0
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dnsmasq: failed to create listening socket for 172.213.0.1: Address already in use
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qemu/create_net.sh tap1
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dnsmasq: failed to create listening socket for 127.0.0.1: Address already in use
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/home/razvan/school/so2/linux.git/tools/labs/templates/assignments/6-e100/nttcp -v -i &
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nttcp-l: nttcp, version 1.47
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nttcp-l: running in inetd mode on port 5037 - ignoring options beside -v and -p
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bind: Address already in use
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nttcp-l: service-socket: bind:: Address already in use, errno=98
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ARCH=x86 qemu/qemu.sh -kernel /home/razvan/school/so2/linux.git/arch/x86/boot/bzImage -device virtio-serial -chardev pty,id=virtiocon0 -device virtconsole,chardev=virtiocon0 -serial pipe:pipe1 -serial pipe:pipe2 -netdev tap,id=tap0,ifname=tap0,script=no,downscript=no -net nic,netdev=tap0,model=virtio -netdev tap,id=tap1,ifname=tap1,script=no,downscript=no -net nic,netdev=tap1,model=i82559er -drive file=core-image-minimal-qemux86.ext4,if=virtio,format=raw -drive file=disk1.img,if=virtio,format=raw -drive file=disk2.img,if=virtio,format=raw --append "root=/dev/vda loglevel=15 console=hvc0" --display none -s
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qemu-system-i386: -chardev pty,id=virtiocon0: char device redirected to /dev/pts/68 (label virtiocon0)
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.. note:: To show the QEMU console use
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Connecting to the VM
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--------------------
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.. code-block:: shell
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Once the machine is booted you can connect to it on the serial port. A
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link named *serial.pts* is created to the right emulated serial port
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and you can use **minicom**, **picocom** to connect to the virtual
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machine from the host:
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.../linux/tools/labs$ QEMU_DISPLAY=gtk make boot
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.. code-block:: shell
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This will show the VGA output and will also give
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access to the standard keyboard.
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$ minicom -D serial.pts
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.. note:: The virtual machine setup scripts and configuration files are located
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in ``tools/labs/qemu/``.
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Poky (Yocto Project Reference Distro) 2.3 qemux86 /dev/hvc0
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.. _vm_interaction_link:
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qemux86 login: root
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root@qemux86:~#
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Connecting to the Virtual Machine
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---------------------------------
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Networking is also setup and you can use ssh to connect to the virtual
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machine after finding out the allocated IP address:
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Once the virtual machine is started you can connect to it on the serial port. A
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symbolic link named ``serial.pts`` is created to the emulated serial port
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device:
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.. code-block:: shell
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$ minicom -D serial.pts
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.../linux/tools/labs$ ls -l serial.pts
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lrwxrwxrwx 1 razvan razvan 11 Apr 1 08:03 serial.pts -> /dev/pts/68
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On the host you use the ``minicom`` command to connect to the virtual machine
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via the ``serial.pts`` link:
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.. code-block:: shell
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.../linux/tools/labs$ minicom -D serial.pts
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[...]
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Poky (Yocto Project Reference Distro) 2.3 qemux86 /dev/hvc0
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qemux86 login: root
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root@qemux86:~# ifconfig
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eth0 Link encap:Ethernet HWaddr 52:54:00:12:34:56
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inet addr:172.20.0.6 Bcast:172.20.0.255 Mask:255.255.255.0
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UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
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RX packets:41 errors:0 dropped:0 overruns:0 frame:0
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TX packets:6 errors:0 dropped:0 overruns:0 carrier:0
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collisions:0 txqueuelen:1000
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RX bytes:7578 (7.4 KiB) TX bytes:1296 (1.2 KiB)
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lo Link encap:Local Loopback
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inet addr:127.0.0.1 Mask:255.0.0.0
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inet6 addr: ::1%134535719/128 Scope:Host
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UP LOOPBACK RUNNING MTU:65536 Metric:1
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RX packets:0 errors:0 dropped:0 overruns:0 frame:0
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TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
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collisions:0 txqueuelen:1000
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RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)
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$ ssh root@172.20.0.6
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The authenticity of host '172.20.0.6 (172.20.0.6)' can't be established.
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RSA key fingerprint is SHA256:CW1opJUHi4LDt1lnKjBVv12kXZ4s+8rreMBm5Jsdm00.
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Are you sure you want to continue connecting (yes/no)? yes
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Warning: Permanently added '172.20.0.6' (RSA) to the list of known hosts.
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root@qemux86:~#
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.. attention:: The Yocto core-image-minimal-qemu does not include an
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SSH server, so you will not able to connect via ssh if
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you are using this image.
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Connecting a debugger to the VM kernel
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--------------------------------------
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You can connect gdb to the running VM kernel and inspect the state of
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the kernel by running the *gdb* target from tools/labs:
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.. code-block :: shell
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$ make gdb
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ln -fs /home/tavi/src/linux/vmlinux vmlinux
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gdb -ex "target remote localhost:1234" vmlinux
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GNU gdb (Ubuntu 7.11.1-0ubuntu1~16.04) 7.11.1
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Copyright (C) 2016 Free Software Foundation, Inc.
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License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
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This is free software: you are free to change and redistribute it.
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There is NO WARRANTY, to the extent permitted by law. Type "show copying"
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and "show warranty" for details.
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This GDB was configured as "x86_64-linux-gnu".
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Type "show configuration" for configuration details.
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For bug reporting instructions, please see:
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<http://www.gnu.org/software/gdb/bugs/>.
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Find the GDB manual and other documentation resources online at:
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<http://www.gnu.org/software/gdb/documentation/>.
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For help, type "help".
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Type "apropos word" to search for commands related to "word"...
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Reading symbols from vmlinux...done.
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Remote debugging using localhost:1234
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0xc13cf2f2 in native_safe_halt () at ./arch/x86/include/asm/irqflags.h:53
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53asm volatile("sti; hlt": : :"memory");
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(gdb) bt
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#0 0xc13cf2f2 in native_safe_halt () at ./arch/x86/include/asm/irqflags.h:53
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#1 arch_safe_halt () at ./arch/x86/include/asm/irqflags.h:95
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#2 default_idle () at arch/x86/kernel/process.c:341
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#3 0xc101f136 in arch_cpu_idle () at arch/x86/kernel/process.c:332
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#4 0xc106a6dd in cpuidle_idle_call () at kernel/sched/idle.c:156
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#5 do_idle () at kernel/sched/idle.c:245
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#6 0xc106a8c5 in cpu_startup_entry (state=<optimized out>)
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at kernel/sched/idle.c:350
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#7 0xc13cb14a in rest_init () at init/main.c:415
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#8 0xc1507a7a in start_kernel () at init/main.c:679
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#9 0xc10001da in startup_32_smp () at arch/x86/kernel/head_32.S:368
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#10 0x00000000 in ?? ()
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(gdb)
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Rebuild the kernel image
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------------------------
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The kernel image is built the first time the VM is started. To rebuild
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the kernel remove the **zImage** file and run the zImage target (or
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start the VM again).
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.. add info about how to update the image
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.. note:: When you connect to the virtual machine, simply enter ``root`` at the
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login prompt and you will get a root console, no password required.
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.. note:: You exit ``minicom`` by pressing ``Ctrl+a`` and then ``x``. You will
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get a confirmation prompt and then you will exit ``minicom``.

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