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New console I/O infrastructure in Xen 1.3

 

 

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Keir.Fraser at cl

Mar 22, 2004, 7:04 AM

Post #1 of 2 (106 views)
Permalink
New console I/O infrastructure in Xen 1.3

Hi,

I thought I'd write a quick note about using the new console I/O
infrastructure in Xen 1.3. Significant new features compared with 1.2,
and with older revisions of 1.3, include:
- bi-directional console access
- log in to a Xenolinux guest OS via its virtual console
- a new terminal client (replaces the use of telnet in character mode)
- proper handling of terminal emulation

Anyway, I hope the following helps!
-- Keir

----------------------------------------------------------------

Domain 0 virtual console
------------------------
The virtual console for domain 0 is shared with Xen's console. For
example, if you specify 'console=com1' as a boot parameter to Xen,
then domain 0 will have bi-directional access to the primary serial
line. Boot-time messages can be directed to the virtual console by
specifying 'console=xencons0' as a boot parameter to Xenolinux.

Connecting to the virtual console
---------------------------------
Domain 0 console may be accessed using the supplied 'miniterm' program
if raw serial access is desired. If the Xen machine is connected to a
serial-port server, then the supplied 'xencons' program may be used to
connect to the appropriate TCP port on the server:
# xencons <server host> <server port>

Logging in via virtual console
------------------------------
It is possible to log in to a guest OS via its virtual console if a
'getty' is running. To achieve this, a suitable device node must be
created, and a new line added to inittab:
# mkdir -p /dev/xen
# mknod /dev/xen/cons c 4 123
# echo "c:2345:respawn:/sbin/mingetty --noclear xen/cons" >>/etc/inittab

[.NOTE to users in the lab -- existing Xen installations may be running
mingetty on /dev/console. This is incorrect behaviour! Please modify
such setups to run mingetty on /dev/xen/cons.]

Additionally, if you wish to allow root logins via the virtual
console, then 'xen/cons' must be added to the trusted tty list in
/etc/securettys.

Virtual console for other domains
---------------------------------
Every guest OS has a virtual console that is accessible via
'console=xencons0' at boot time, or mingetty running on
/dev/xen/cons. However, domains other than domain 0 do not have access
to the physical serial line. Instead, their console data is sent to
and from a control daemon running in domain 0. When properly
installed, this daemon can be started from the init scripts (e.g.,
rc.local):
# /usr/sbin/xend start

Note that, when a domain is created using xc_dom_create.py, xend MUST
be running. If everything is set up correctly then xc_dom_create will
print the local TCP port to which you should connect to perform
console I/O. A suitable console client is provided by the Python
module xenctl.console_client: running this module from the command
line with <host> and <port> parameters will start a terminal
session. This module is also installed as /usr/bin/xencons, from a
copy in tools/misc/xencons. For example:
# xencons localhost 9600

An alternative to manually running a terminal client is to specify
'-c' to xc_dom_create.py, or add 'auto_console=True' to the defaults
file. This will cause xc_dom_create.py to automatically become the
console terminal after starting the domain.


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_______________________________________________
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Keir.Fraser at cl

Mar 22, 2004, 7:04 AM

Post #2 of 2 (102 views)
Permalink
New console I/O infrastructure in Xen 1.3 [In reply to]

Hi,

I thought I'd write a quick note about using the new console I/O
infrastructure in Xen 1.3. Significant new features compared with 1.2,
and with older revisions of 1.3, include:
- bi-directional console access
- log in to a Xenolinux guest OS via its virtual console
- a new terminal client (replaces the use of telnet in character mode)
- proper handling of terminal emulation

Anyway, I hope the following helps!
-- Keir

----------------------------------------------------------------

Domain 0 virtual console
------------------------
The virtual console for domain 0 is shared with Xen's console. For
example, if you specify 'console=com1' as a boot parameter to Xen,
then domain 0 will have bi-directional access to the primary serial
line. Boot-time messages can be directed to the virtual console by
specifying 'console=xencons0' as a boot parameter to Xenolinux.

Connecting to the virtual console
---------------------------------
Domain 0 console may be accessed using the supplied 'miniterm' program
if raw serial access is desired. If the Xen machine is connected to a
serial-port server, then the supplied 'xencons' program may be used to
connect to the appropriate TCP port on the server:
# xencons <server host> <server port>

Logging in via virtual console
------------------------------
It is possible to log in to a guest OS via its virtual console if a
'getty' is running. To achieve this, a suitable device node must be
created, and a new line added to inittab:
# mkdir -p /dev/xen
# mknod /dev/xen/cons c 4 123
# echo "c:2345:respawn:/sbin/mingetty --noclear xen/cons" >>/etc/inittab

[.NOTE to users in the lab -- existing Xen installations may be running
mingetty on /dev/console. This is incorrect behaviour! Please modify
such setups to run mingetty on /dev/xen/cons.]

Additionally, if you wish to allow root logins via the virtual
console, then 'xen/cons' must be added to the trusted tty list in
/etc/securettys.

Virtual console for other domains
---------------------------------
Every guest OS has a virtual console that is accessible via
'console=xencons0' at boot time, or mingetty running on
/dev/xen/cons. However, domains other than domain 0 do not have access
to the physical serial line. Instead, their console data is sent to
and from a control daemon running in domain 0. When properly
installed, this daemon can be started from the init scripts (e.g.,
rc.local):
# /usr/sbin/xend start

Note that, when a domain is created using xc_dom_create.py, xend MUST
be running. If everything is set up correctly then xc_dom_create will
print the local TCP port to which you should connect to perform
console I/O. A suitable console client is provided by the Python
module xenctl.console_client: running this module from the command
line with <host> and <port> parameters will start a terminal
session. This module is also installed as /usr/bin/xencons, from a
copy in tools/misc/xencons. For example:
# xencons localhost 9600

An alternative to manually running a terminal client is to specify
'-c' to xc_dom_create.py, or add 'auto_console=True' to the defaults
file. This will cause xc_dom_create.py to automatically become the
console terminal after starting the domain.


-------------------------------------------------------
This SF.Net email is sponsored by: IBM Linux Tutorials
Free Linux tutorial presented by Daniel Robbins, President and CEO of
GenToo technologies. Learn everything from fundamentals to system
administration.http://ads.osdn.com/?ad_id=1470&alloc_id=3638&op=click
_______________________________________________
Xen-devel mailing list
Xen-devel [at] lists
https://lists.sourceforge.net/lists/listinfo/xen-devel

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