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Title: Xen console grabbded /dev/ttyS0

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This week I started on evaluating an iSCSI storage system which should get connected to a Xen-enabled host. An article covering this particular topic is in preparation.

Since the iSCSI device offered management capabilities over serial console I though to attach it to COM1 (/dev/ttyS0) of my host system.
This is well the point when I noticed that Xen had already grabbed /dev/ttyS0. Since my host system offered only one serial port and I didn't have a spare serial server at hands I needed to change this behaviour to get it working.

By means of 'dmesg' it can be easily verified if Xen grabbed the serial port:

# dmesg|grep ttyS0
Xen virtual console successfully installed as ttyS0
Then make sure you know which kernel version you're running:

# uname -r
Linux gic-ftp-lin-001.genotec.ch 2.6.18-8.el5xen #1 SMP Fri Jan 26 14:29:35 EST 2007 x86_64 x86_64 x86_64 GNU/Linux
Look for the corresponding kernel section in your grub.conf (or whatever boot loader you use).

title Red Hat Enterprise Linux Server (2.6.18-8.el5xen)
        root (hd0,0)
        kernel /boot/xen.gz-2.6.18-8.el5
        module /boot/vmlinuz-2.6.18-8.el5xen ro root=LABEL=/
        module /boot/initrd-2.6.18-8.el5xen.img
Then add the 'xencons' option to the module line stating the kernel arguments.

title Red Hat Enterprise Linux Server (2.6.18-8.el5xen)
        root (hd0,0)
        kernel /boot/xen.gz-2.6.18-8.el5
        module /boot/vmlinuz-2.6.18-8.el5xen ro root=LABEL=/ xencons=tty6
        module /boot/initrd-2.6.18-8.el5xen.img
In this case I added 'xencons=tty6' to have Xen grab /dev/tty6 for it's console.

Other possibilities are:


xencons=off
 
disable console at all


xencons=ttyX
 
attach console to /dev/ttyX


xencons=ttySX
 
attach console to /dev/ttySX


xencons=xvcX
 
attach console to /dev/xvcX


After changing this line and rebooting the system I could finally connect my iSCSI's serial terminal.

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Images: 

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Post date: 2007-06-30 14:00:21

Post date GMT: 2007-06-30 13:00:21

Post modified date: 2010-12-18 17:16:13

Post modified date GMT: 2010-12-18 16:16:13



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