KVM Guest installed from console. But how to get to the guest's console?
Solution 1
I copied --extra-args='console=ttyS0'
somewhere from Internet last time, it works!
- No need for two "console" commands, that just opens two consoles instead of one
- No need to manually specify the baud rate.
- "--serial" option has been deprecated
- The RedHat console device is "/dev/ttyS0", not "/dev/tty0"
See: http://anaconda-installer.readthedocs.io/en/latest/boot-options.html
Solution 2
--nographics
is used, and you have no console set up in the guest, besides the tty0 console. If you want a graphical console, especially available remotely you'd need to enable vga and vnc, or qxl and spice. this is an example: http://www.linux-kvm.com/content/tip-how-run-headless-guest-machine-using-vnc-kvm
http://www.linux-kvm.com/content/running-kvm-nographics-no-console-output or http://ubuntuforums.org/showpost.php?p=9610421&postcount=7 is also a solution.
Solution 3
I had a similar problem when trying to perform a text-only installation of CentOS. It all boils down to adding kernel arguments for specifying serial output console console=ttyS0
so that you can then connect to it when --graphics none
or --nographics
is used. From virt-install
's manual:
--graphics none
No graphical console will be allocated for the guest. Fully virtualized guests (Xen FV or QEmu/KVM) will need to have a text console configured on the first serial port in the guest (this can be done via the --extra-args option). Xen PV will set this up automatically. The command 'virsh console NAME' can be used to connect to the serial device.
I've managed to solve it in two ways:
- by modifying the iso image and using the
--cdrom
option - by exposing the iso image as NFS share and using the
--location
option with--extra-args
1. Modifying the image
In order to modify the kernel parameters on the iso installation disk:
- Get a program that allows manipulating images, for example, isomaster.
- Go to to the
isolinux/isolinux.cfg
file on the image, open it, find the first line withinitrd=
on it and appendconsole=ttyS0
to it and all other lines that have the mentioned parameter. - Save the file and the image.
-
Use the modified image with
virt-install
as usual, e.g.:$ sudo virt-install --name centos-vm --ram 1024 --disk path=/home/user/domains/centos-vm --cdrom /home/user/images/centos-modified.iso --os-type linux --nographics --accelerate
Done.
2. Using a NFS share
-
Mount the image:
$ sudo mount -o loop,unhide -t iso9660 -r /home/user/images/CentOS.iso /home/user/mnt/cdrom
Start the NFS service if not running:
service nfs start
-
Add the following line in
/etc/exports
to make it available to the clients:/home/user/mnt/cdrom *(ro,insecure,all_squash)
-
Refresh the system's export table with:
$ exportfs -r
-
Use the share with
virt-install
making sure to inculde the--extra-args
, e.g.:$ sudo virt-install --name centos-vm --ram 1024 --disk path=/home/user/domains/centos-vm --location /home/user/mnt/cdrom --os-type linux --nographics --accelerate --extra-args="console=ttyS0"
During the installation of CentOS you get a prompt asking about the location of the installation files. You have to type the address of your machine and the full path to the share.
Done.
Solution 4
You need to run the Fedora installer in text mode. Try adding 'text' to the extra args. Alternatively, you could try adding "vnc" which will allow you to connect to the installer over VNC once it is started
Solution 5
I've been doing my installations for a while now using cobbler and koan. Within cobbler I set my kernel options like so under my Centos60-x86_64 profile:
Kernel Options: serial console=ttyS0,115200
Kernel Options (Post Install): console=ttyS0,115200
After boot you can use console=tty0 console=ttS0,115200 to get console to show on two devices; this doesn't work for installation. If you edit the grub options under /etc/grub and regenerate grub.conf the serial console settings will survive a kernel upgrade. Add "text" to the kernel command line to prevent installer from starting a GUI.
When my KVM guest instances start I then connect to them while logged into the KVM host and connect to a guest's console like this:
[root@vmhost ~]# virsh console guestvm
I then see this in my shell:
Connected to domain guestvm
Escape character is ^]
CentOS Linux release 6.0 (Final)
Kernel 2.6.32-71.el6.x86_64 on an x86_64
guestvm login:
One final note, when I tell koan to start building one of my KVM guests, I call it with the --nogfx switch like so:
koan --server 192.168.1.1 --virt --nogfx --system=guestvm
badbishop
Updated on September 18, 2022Comments
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badbishop almost 2 years
I'm trying to install a fully virtualized guest (Fedora 14 x86_64) on KVM (RHEL 6), using command-line only (both hypervisor and guest). It goes without errors, and without a tangible result . I'd like to know how to do a text-only installation.
So, here's what I've done:
# virt-install \ --name=FE --ram=756 --vcpus=1 \ --file=/var/lib/libvirt/images/FE.img --network bridge:br0 \ --nographics --os-type=linux \ --extra-args='console=tty0' -v \ --cdrom=/media/usb/Fedora-14-x86_64-Live-Desktop.iso Starting install... Creating domain... | 0 B 00:00 Connected to domain FE Escape character is ^] ÿ
Now what? As I understand after googling for a couple of days, I should see the guest's output from the text installation, but nothing happens. virt-viewer cannot connect to it, kindly suggesting that I explore all the options by adding --help (which I did). If I reconnect with virsh, I see this:
Domain installation still in progress. You can reconnect to the console to complete the installation process. [root@v ~] # virsh console FEConnected to domain FE Escape character is ^]
This shows that VM is running
# virsh list Id Name State ---------------------------------- 8 FE running
Qemu log:
LC_ALL=C PATH=/sbin:/usr/sbin:/bin:/usr/bin /usr/libexec/qemu-kvm -S -M rhel6.0.0 -enable-kvm -m 756 -smp 1,sockets=1,cores=1,threads=1 -name FE -uuid 6989d008-7c89-424c-d2d3-f41235c57a18 -nographic -nodefconfig -nodefaults -chardev socket,id=monitor,path=/var/lib/libvirt/qemu/FE.monitor,server,nowait -mon chardev=monitor,mode=control -rtc base=utc -no-reboot -boot d -drive file=/var/lib/libvirt/images/FE.img,if=none,id=drive-ide0-0-0,format=raw,cache=none -device ide-drive,bus=ide.0,unit=0,drive=drive-ide0-0-0,id=ide0-0-0 -drive file=/media/usb/Fedora-14-x86_64-Live-Desktop.iso,if=none,media=cdrom,id=drive-ide0-1-0,readonly=on,format=raw -device ide-drive,bus=ide.1,unit=0,drive=drive-ide0-1-0,id=ide0-1-0 -netdev tap,fd=20,id=hostnet0 -device rtl8139,netdev=hostnet0,id=net0,mac=52:54:00:0a:65:8d,bus=pci.0,addr=0x2 -chardev pty,id=serial0 -device isa-serial,chardev=serial0 -usb -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x3 char device redirected to /dev/pts/1
Output of /etc/libvirt/qemu/FE.xml
# cat /etc/libvirt/qemu/FE.xml <domain type='kvm'> <name>FE</name> <uuid>6989d008-7c89-424c-d2d3-f41235c57a18</uuid> <memory>774144</memory> <currentMemory>774144</currentMemory> <vcpu>1</vcpu> <os> <type arch='x86_64' machine='rhel6.0.0'>hvm</type> <boot dev='hd'/> </os> <features> <acpi/> <apic/> <pae/> </features> <clock offset='utc'/> <on_poweroff>destroy</on_poweroff> <on_reboot>restart</on_reboot> <on_crash>restart</on_crash> <devices> <emulator>/usr/libexec/qemu-kvm</emulator> <disk type='file' device='disk'> <driver name='qemu' type='raw' cache='none'/> <source file='/var/lib/libvirt/images/FE.img'/> <target dev='hda' bus='ide'/> <address type='drive' controller='0' bus='0' unit='0'/> </disk> <disk type='block' device='cdrom'> <driver name='qemu' type='raw'/> <target dev='hdc' bus='ide'/> <readonly/> <address type='drive' controller='0' bus='1' unit='0'/> </disk> <controller type='ide' index='0'> <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x1'/> </controller> <interface type='bridge'> <mac address='52:54:00:0a:65:8d'/> <source bridge='br0'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/> </interface> <serial type='pty'> <target port='0'/> </serial> <console type='pty'> <target port='0'/> </console> <memballoon model='virtio'> <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/> </memballoon> </devices> </domain>
I'm obviously missing something that many others don't, but what is it? Thanx in advance!
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slm about 13 yearsHow were you able to get the --extra-args switch to work with --cdrom? According to the virt-install man page --extra-args only works with --location?
-
some over 11 yearsI removed
--network bridge:br0
, changedcdrom
tolocation
, andextra-args
to--extra-args='console=tty0 console=ttyS0,115200n8 serial'
and it worked! -
twan163 over 9 yearsI only changed cdrom to location and added "extra-args". No need to remove the --network options.
-
Rick Chatham almost 9 yearsFor whatever reason
--cdrom
doesn't work with extra-args but--location
(or-l
) does. Same path and everything.
-
-
badbishop about 13 yearsThanks for answering, dyasny. Picking your points: 1. No, I do NOT want a graphical console (see my post) 2. Yes, I have been trying this and similar solutions. It didn't work for me.
-
Jonathan Ross about 13 yearsBTW
--extra-args=
takes other console settings directly too. -
badbishop about 13 yearsAccording to the text you've quoted, I need to modify /etc/inittab on guest. The whole problem is: how do I interact with guest? Sorry, I'm not getting it.
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Jonathan Ross about 13 yearsSorry see edit, I wasn't very clear.
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badbishop about 13 yearsYes, I've tried --extra-args='console=ttyS0' as well before posting the question.
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Jonathan Ross about 13 yearsSorry I meant
console=ttyS0,115200
and presumably there are other parameters for this that you can try. I'd still guess you have a misconfigured console of some description. -
David Corsalini about 13 yearsI'd try to ask on linux-kvm.org or on the libvirt mailing list
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katriel almost 13 yearsChecked it out, for a newer libvirt, you can't use -x and --cdrom. Try mounting the cdrom somewhere on the network and using --location somewhere.com/mounted-iso --graphics none --extra-args "console=ttyS0,115200 text headless"
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public_name over 9 yearsi have tried your second method to mount iso file but i got this error Starting install... Retrieving file .treeinfo... | 552 B 00:00:00 ERROR No option 'kernel' in section: 'images-x86_64' i mount iso file to /mnt and use --location /mnt in virt-install
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Rick Chatham almost 9 years@public_name Try not mounting the iso but just specifying the path to the iso after
--location
like--location /tmp/centos6.iso
. -
John McGehee almost 6 yearsWorked on Ubuntu 16, editing isolinux/txt.cfg instead of isolinux/isolinux.cfg.