OpenStack requires a system that has the virtualisation feature, but you might want to test it on the virtual guest before actually install it in bare metal system. In that case, you can achieve it by enabling nested virtualisation feature in recent Linux distribution. You can find if your distro has that feature by checking… Continue reading How to install OpenStack on Fedora VM
If you made changes in udev rules, you might want to reboot to apply the changes. But, there's a simpler method than system reboot. It depends which version you are using. I'll put RHEL5 and RHEL6 commands which might cover most scenario. In RHEL5 $ yum install udev $ udevcontrol reload_rules $ /sbin/start_udev $ udevtrigger… Continue reading How to reload udev rules
If you want to change your Mac OS X's hostname from the default, you can use the following command. $ sudo scutil --set HostName If you are in the terminal, you need to restart the terminal to get the changed host name.
cinder documentation says you need to install below packages in Fedora/RHEL, but it's not working as some packages are missing. $ sudo yum install python-devel openssl-devel python-pip git libmysqlclient-dev libqp-dev I had to test one by one and below seems working perfectly. $ sudo yum install python-devel openssl-devel python-pip git mysql-devel libpqxx-devel
If you are failing installing vmware-tools in Fedora 18 with the following message, it might be caused of the changes in Fedora 18 kernel-revel package. The path "" is not a valid path to the .... Here's the simple command that will resolve the issue. It also works for latest Fedora 17 issue. $ cp… Continue reading vmware-tools installation failure in Fedora 18?
To use colours in your Mac terminal, you just need to put below in your ~/.bash_profile export CLICOLOR=1 export LSCOLORS=ExFxBxDxCxegedabagacad export GREP_OPTIONS='--color=auto' alias ls='ls -GFh' For the vim, below would be work by put in ~/.vimrc set nocompatible " must be the first line set tabstop=4 shiftwidth=4 softtabstop=4 filetype on filetype indent on filetype plugin… Continue reading Use colours in your Mac terminal
If you are interested in Red Hat Virtualization and couldn't afford to buy machines for the hypervisor, using VMWare would be one possible cheaper way to achieve it. By using nested virtualisation technology, you can easily build an environment. Only thing you need to before the installation is making some changes in the vmx file… Continue reading Installing RHEV Hypervisor on VMWare Fusion
One problem with kprobes is that you can't check validity of the arguments passed to the function you are monitoring. For that matter, jprobes comes in. It's basically make a wrapper for the existing function and will be called instead without make any changes to the existing function. jprobes is an extention to the kprobes… Continue reading Tracing a function with jprobes
As the kernel is running on top of all other services, it's hard to debug it in a live system. You can use 'gdb' on a live system, but you only can check the current values of some exported symbols. You can't use breakpoint on a running kernel. If you set a breakpoint, it'll stop… Continue reading Tracing an instruction or a function with kprobes
Basics about SysRq During the kernel debugging, you can use SysRq to get some details about the system status at some point or to execute some commands without typing the command. We can use one of the below method to trigger the operation. Method 1. $ echo 1 > /proc/sys/kernel/sysrq Press 'Alt-SysRq-[key]' combination to trigger… Continue reading Extending SysRq
There's a time you want to check the local variables or other entries in the stack. Below is an example that was crashed in 'kmem_freepages' and needed to check why it's crashed whiling freeing it. PID: 26 TASK: ffff81027f9197a0 CPU: 0 COMMAND: "events/0" #0 [ffff81027f92fa90] crash_kexec at ffffffff800aaa0c #1 [ffff81027f92fb50] __die at ffffffff8006520f #2 [ffff81027f92fb90]… Continue reading Jump into vmcore analysis – Step 8
If the vmcore was generated by human and you want to check who actually was, you might need to check the related process. There are various options in 'ps' command, so, you would be able to check it with below steps. crash> ps -a 6326 PID: 6326 TASK: ffff810402165820 CPU: 1 COMMAND: "fuser" ARG: fuser… Continue reading Jump into vmcore analysis – Step 7