SSW logo Blog - Michael's Musings

Sat, 06 Aug 2016

Putting a comma in a KVM/QEMU SMBios name

Not well documented in qemu-system(1), but if you want to have an SMBios name like: "VMware, Inc", then you need to set it as:

kvm -smbios type=1,manufacturer="VMware,, Inc.",product="VMware Virtual Platform",version="None",serial="VMware-77 bb aa bb cc dd ee ff-11 22 33 44 55 66 77 88"

This results in something like:

System Information
        Manufacturer: VMware, Inc.
        Product Name: VMware Virtual Platform
        Version: None
        Serial Number: VMware-stuff

in your dmidecode, which you may need if you are moving from VMware to another platform, and have things inside that care.

Tue, 14 Sep 2010

Reset password for MSSQL

If you are using RHEV Manager, you'll have a whole headache of Windows 2008 and 2008 SQL Server crap. After an upgrade, we realized that we did not have the SQL server account password used. Redhat told us:

To recovery of sql server sa password should be easy by using the local windows administrator credentials to login and set the sa password.

sqlcmd -S .\sqlexpress -drhevm -Q "ALTER LOGIN sa WITH PASSWORD = 'new_password'"

Wed, 08 Sep 2010

How to run XEN on Ubuntu Lucid

http://www.chrisk.de/blog/2008/12/how-to-run-xen-in-ubuntu-intrepid-without-compiling-a-kernel-by-yourself/

documents how to install the Debian DOM0 kernel on Ubuntu LTS. This is an update.

aptitude install libuuid-perl
wget http://ftp.de.debian.org/debian/pool/main/l/linux-2.6/linux-image-2.6.32-5-xen-amd64_2.6.32-21_amd64.deb
wget http://ftp.de.debian.org/debian/pool/main/l/linux-2.6/linux-modules-2.6.26-2-xen-amd64_2.6.26-25_amd64.deb
wget http://ftp.de.debian.org/debian/pool/main/l/linux-2.6/linux-base_2.6.32-21_all.deb
dpkg -i linux-image-2.6.32-5-xen-amd64_2.6.32-21_amd64.deb linux-modules-2.6.26-2-xen-amd64_2.6.26-25_amd64.deb linux-base_2.6.32-21_all.deb

Sat, 26 Dec 2009

IPv6 with mcast UserModeLinux backends

I am doing some work with IPv6. (see http://bluerose.sandelman.ca/projects/show/unstrung )

I have a test network shown at: http://bluerose.sandelman.ca/repositories/changes/unstrung/doc/network-1.png

In automated testing I would normally use the daemon mode, with uml_netjig. In casual use, I was using the mcast backend, because it has fewer moving parts.... but my network interfaces kept remaining in state "tentative" and I could not send packets.

What was the problem, I debugging for awhile through the IPv6 code, and finally thought that it had something to do with the UserModeLinux network interface never providing low-level LINK "UP" signal, and so it never did Duplicate Address Discovery, and remove the tentative mark.

5: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qlen 1000
    inet6 fe80::1000:ff:fedc:bcff/64 scope link tentative
       valid_lft forever preferred_lft forever
6: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qlen 1000
    inet6 fe80::1000:ff:fe64:6423/64 scope link tentative
       valid_lft forever preferred_lft forever

Note that it says "tentative".

NO! DAD was occuring just fine, but it FAILS. Why? Because it thinks it has a duplicate... finally I noticed

eth0: duplicate address detected!
eth1: duplicate address detected!

Why is this? It's because the mcast interface gets a copy of the packets that are output. I.e. it hears itself. DAD should work even when that happens, I think.

I need to look at whether the mcast interface should be fixed (remember it's own packets and ignore them? Drop packets that originate from it's own MAC address?), or should DAD be fixed?