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Howto connect to a terminal in an emalated linux-livecd?

DISCUSSION Oliver Rath 3 participants 3 messages Sep 11, 2014 – Sep 12, 2014 KVM

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Oliver Rath

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Hi list,

after hours for searching in google-world, i didnt find any appropriate for this problem:

I want to boot a live-cd (i.e. ubuntu 14.04.1-desktop) in qemu, which starts with an graphical interface, done i.e. by

qemu-system-x86_64 -m 3G -smp 2 -drive file=ubuntu-14.04.1-desktop-i386.iso,media=cdrom,if=virtio --enable-kvm

Now i want to access to the console of the ubuntu-livecd. At the moment i can do this over changing to text mode via

sendkey ctrl-alt-f1

in qemu-console (Alt-2), then switching back to qemu-window (alt-1). Now i have access to tty1 of my livecd.

But IMHO there should be a more simple way to access to such a console with qemu, i.e. through a pipe, a serial console etc., but i didnt found anything working. The best i got was with -chardev pty,id=myid, which resulted in a "char device redirected to /dev/pts/0 (label myid)". But with a "screen /dev/pts/0" i wasnt able to see any input or output.

ssh is unfortunatly not available at this time on the livecd (so i could connect i.e. via -net user,hostfwd:tcp:10022-:22)

Any hints to connect directly to a console in an emulated linux?

Tfh!
Oliver

#1 lore raw
Quoted 23 lines · Oliver Rath

after hours for searching in google-world, i didnt find any appropriate for this problem:

I want to boot a live-cd (i.e. ubuntu 14.04.1-desktop) in qemu, which starts with an graphical interface, done i.e. by

qemu-system-x86_64 -m 3G -smp 2 -drive file=ubuntu-14.04.1-desktop-i386.iso,media=cdrom,if=virtio --enable-kvm

Now i want to access to the console of the ubuntu-livecd. At the moment i can do this over changing to text mode via

sendkey ctrl-alt-f1

in qemu-console (Alt-2), then switching back to qemu-window (alt-1). Now i have access to tty1 of my livecd.

But IMHO there should be a more simple way to access to such a console with qemu, i.e. through a pipe, a serial console etc., but i didnt found anything working. The best i got was with -chardev pty,id=myid, which resulted in a "char device redirected to /dev/pts/0 (label myid)". But with a "screen /dev/pts/0" i wasnt able to see any input or output.

Quoted 4 lines

ssh is unfortunatly not available at this time on the livecd (so i could connect i.e. via -net user,hostfwd:tcp:10022-:22)

Any hints to connect directly to a console in an emulated linux?

I use the serial console:

  $ qemu-system-x86_64 -serial stdio ...

Make sure the guest has console=ttyS0 on the kernel command-line.

Stefan

#2 lore raw
Quoted 27 lines · Stefan Hajnoczi
Quoted 26 lines · Oliver Rath

after hours for searching in google-world, i didnt find any appropriate for this problem:

I want to boot a live-cd (i.e. ubuntu 14.04.1-desktop) in qemu, which starts with an graphical interface, done i.e. by

qemu-system-x86_64 -m 3G -smp 2 -drive file=ubuntu-14.04.1-desktop-i386.iso,media=cdrom,if=virtio --enable-kvm

Now i want to access to the console of the ubuntu-livecd. At the moment i can do this over changing to text mode via

sendkey ctrl-alt-f1

in qemu-console (Alt-2), then switching back to qemu-window (alt-1). Now i have access to tty1 of my livecd.

But IMHO there should be a more simple way to access to such a console with qemu, i.e. through a pipe, a serial console etc., but i didnt found anything working. The best i got was with -chardev pty,id=myid, which resulted in a "char device redirected to /dev/pts/0 (label myid)". But with a "screen /dev/pts/0" i wasnt able to see any input or output.

ssh is unfortunatly not available at this time on the livecd (so i could connect i.e. via -net user,hostfwd:tcp:10022-:22)

Quoted 7 lines
Quoted 1 line

Any hints to connect directly to a console in an emulated linux?

I use the serial console:

  $ qemu-system-x86_64 -serial stdio ...

Make sure the guest has console=ttyS0 on the kernel command-line.

Just to add a little more to what Stefan wrote, here's a working CLI (not be the most optimal) I use w/ serial console:

  $ /usr/bin/qemu-system-x86_64 -m 2048 \
      -nographic -nodefconfig -nodefaults \
      -machine accel=kvm -m 2048 \
      -drive file=./snap1-f20vm.qcow2,if=ide,format=qcow2 \
      -serial stdio

And, a little more info here[1]

[1] http://rwmj.wordpress.com/2011/07/08/setting-up-a-serial-console-in-qemu-and-libvirt/

--
/kashyap