Re: How to exit console in L2 vm?

[Yalan Zhang]

I see. Thank you for the detailed explanation.


---
Best Regards,
Yalan Zhang
IRC: yalzhang


On Mon, Nov 30, 2020 at 3:31 PM Peter Krempa  wrote:

> On Mon, Nov 30, 2020 at 14:50:33 +0800, Yalan Zhang wrote:
> > Hi,
> >
> > I have a question about nested virtualization. The scenario is as below:
> > 1. Prepare the nested environment, start L2 guest.
> > 2. On the host, connect the L1 vm console, then on L1 guest, connect the
> L2
> > guest console:
> > (host)# virsh console L1_vm
> > Connected to domain L1_vm
> > Escape character is ^] (Ctrl + ])
> > ...
> > (L1 vm)# virsh console L2_vm
> > Connected to domain L2_vm
> > Escape character is ^] (Ctrl + ])
> > ...
> > (L2 vm)# <=== press " ^] " to exit the console, it return to the **host**
> > (host)#
> >
> > Is it expected that "^]" in L2 guest will exit thoroughly to the host,
> not
> > the L1 guest?
>
> Yes it is expected since the keystroke goes through L1 first.
>
> You can use the '-e' switch of virsh to set the console escape character
> in one of the clients differently:
>
> $ virsh -e '^[' console 1
> Connected to domain fedora32
> Escape character is ^[ (Ctrl + [)
>
>

Re: How to exit console in L2 vm?

[Yukin Chan]

Hi Yalan,

I am not certain about that but I think it is as expected. When you send ^]
(which is the common escape sequence used in telnet) on the host L1 console
wil receive the key codes and forward to L2 console so the latter one
should exit. But L1 console also receives the escape character itself so it
also exits.

A solution it to set a different escape sequence for the consoles[1]:

>
>- -e, --escape string
>
> Set alternative escape sequence for console command. By default, telnet's
> ^] is used. Allowed characters when using hat notation are: alphabetic
> character, @, [, ], , ^, _.
>

So that L1 console will not exit when forwarding the sequence to L2 console
without quitting itself.

[1]: https://libvirt.org/manpages/virsh.html#description

Yalan Zhang  於 2020年11月30日 週一 下午2:55寫道：

> Hi,
>
> I have a question about nested virtualization. The scenario is as below:
> 1. Prepare the nested environment, start L2 guest.
> 2. On the host, connect the L1 vm console, then on L1 guest, connect the
> L2 guest console:
> (host)# virsh console L1_vm
> Connected to domain L1_vm
> Escape character is ^] (Ctrl + ])
> ...
> (L1 vm)# virsh console L2_vm
> Connected to domain L2_vm
> Escape character is ^] (Ctrl + ])
> ...
> (L2 vm)# <=== press " ^] " to exit the console, it return to the **host**
> (host)#
>
> Is it expected that "^]" in L2 guest will exit thoroughly to the host, not
> the L1 guest?
> Thank you!
>
>
> ---
> Best Regards,
> Yalan Zhang
> IRC: yalzhang
>


-- 
Regards,

Yukin CHAN, ISTQB

She / Her / Hers

Software Quality Engineer, Virtualization

Red Hat APAC 

9 floor, Raycom Infotech Park, North Tower C

2 Kexueyuan Nanlu, Haidian District, Beijing, China

T: 86-10-65627449

PGP: AC7BCF02F44FA43F940A3B9A25D5E545D2C3D639

Re: How to exit console in L2 vm?

[Peter Krempa]

On Mon, Nov 30, 2020 at 14:50:33 +0800, Yalan Zhang wrote:
> Hi,
> 
> I have a question about nested virtualization. The scenario is as below:
> 1. Prepare the nested environment, start L2 guest.
> 2. On the host, connect the L1 vm console, then on L1 guest, connect the L2
> guest console:
> (host)# virsh console L1_vm
> Connected to domain L1_vm
> Escape character is ^] (Ctrl + ])
> ...
> (L1 vm)# virsh console L2_vm
> Connected to domain L2_vm
> Escape character is ^] (Ctrl + ])
> ...
> (L2 vm)# <=== press " ^] " to exit the console, it return to the **host**
> (host)#
> 
> Is it expected that "^]" in L2 guest will exit thoroughly to the host, not
> the L1 guest?

Yes it is expected since the keystroke goes through L1 first.

You can use the '-e' switch of virsh to set the console escape character
in one of the clients differently:

$ virsh -e '^[' console 1
Connected to domain fedora32
Escape character is ^[ (Ctrl + [)

Re: How to exit console in L2 vm?

[Pavel Hrdina]

On Mon, Nov 30, 2020 at 02:50:33PM +0800, Yalan Zhang wrote:
> Hi,
> 
> I have a question about nested virtualization. The scenario is as below:
> 1. Prepare the nested environment, start L2 guest.
> 2. On the host, connect the L1 vm console, then on L1 guest, connect the L2
> guest console:
> (host)# virsh console L1_vm
> Connected to domain L1_vm
> Escape character is ^] (Ctrl + ])
> ...
> (L1 vm)# virsh console L2_vm
> Connected to domain L2_vm
> Escape character is ^] (Ctrl + ])
> ...
> (L2 vm)# <=== press " ^] " to exit the console, it return to the **host**
> (host)#
> 
> Is it expected that "^]" in L2 guest will exit thoroughly to the host, not
> the L1 guest?
> Thank you!

Hi,

With virsh you can configure different escape character.

It could look like this for example:

On host you would run:

virsh console L1_vm


and in the L1 VM you would run this:

virsh -e ^[ console L2_vm


For more info check the virsh man page.

Pavel


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How to exit console in L2 vm?

[Yalan Zhang]

Hi,

I have a question about nested virtualization. The scenario is as below:
1. Prepare the nested environment, start L2 guest.
2. On the host, connect the L1 vm console, then on L1 guest, connect the L2
guest console:
(host)# virsh console L1_vm
Connected to domain L1_vm
Escape character is ^] (Ctrl + ])
...
(L1 vm)# virsh console L2_vm
Connected to domain L2_vm
Escape character is ^] (Ctrl + ])
...
(L2 vm)# <=== press " ^] " to exit the console, it return to the **host**
(host)#

Is it expected that "^]" in L2 guest will exit thoroughly to the host, not
the L1 guest?
Thank you!


---
Best Regards,
Yalan Zhang
IRC: yalzhang