In a Linux system, we may have multiple kernels installed. Usually, it is the latest kernel configured to be the default one the system boot loader will use during automatic boot if there is no manual kernel choosing. In many cases, such as there is no driver ready yet for some devices in newer kernels,…
How to detect whether Linux runs in UEFI or BIOS mode inside the Linux itself without needed to boot the the management console of the mother board? You can detect whether Linux runs in EFI mode by checking whether /sys/firmware/efi exist. In bash, you can test by [ -d /sys/firmware/efi/ ] This technique is used…
I need to add nomodeset to make my GPU card work on Linux. Latest Fedora and Ubuntu and their derives use grub2. How to add nomodeset permanently to grub2 on Fedora and Ubuntu? The parameters grub2 will use are stored in its grub.cfg file. The grub.cfg file is generated from grub’s default settings file /etc/default/grub….
After a kernel panic, it is impossible to remotely connect to the Linux server to reboot it by SSH. How to make the panic kernel automatically reboot itself? Linux kernel has a nice feature that reboots itself after a timeout when a kernel panic happened. Usually, it is disabled by default. To turn it on,…
How to boot Linux Mint to the console by default? (that is, the run level 3). 2 methods introduced here to boot Linux Mint to console/command line. Method 1 (may only work for earlier releases; check method 2 below): set kernel option. Edit /etc/default/grub and add text to GRUB_CMDLINE_LINUX_DEFAULT: GRUB_CMDLINE_LINUX_DEFAULT=”quiet splash text” Then, re-generate grub…
How to manually set the boot entry for Windows in grub2? Suppose that your Windows is installed on the first partition of the first disk (hd0,1) (yes, it’s right, that is (hd0, 1) if your distribution has not modified grub2’s default behavior) in NTFS format. You can boot your Windows in grub2 by: insmod ntfs…
How to upgrade Fedora 19 to Fedora 20 through the network? The tool for Fedora to upgrade the distribution is FedUp. Check this page for how to upgrade Fedora 19 to Fedora 20: http://fedoraproject.org/wiki/FedUp#How_Can_I_Upgrade_My_System_with_FedUp.3F Be sure to check the bugs in Fedora 20 before the upgrading: http://fedoraproject.org/wiki/Common_F20_bugs#Upgrade_issues Generally, it contains 3 steps: Preparation # yum…
Grub2: How to boot Fedora to an old kernel? The old kernel is a submenu under “Advanced options for Fedora”. It is not shown if I follow the instruction that # grep menuentry /boot/grub2/grub.cfg | cut -d “‘” -f2. The old kernel in grub2 is in a submenu entry in a menu. The key is…
Building Linux kernel may sound a complex and geek-only thing. However, as Linux kernel itself has much less depended tools/packages compared to other software packages, it is quite easy to compile, build and install a Linux kernel from the source code in an existing Linux OS. Building Linux kernel is needed if you need to…
Grub2 config file may need to be re-generated after changing Grub2 configurations such as configuration changes and setting default boot entries. The Grub2’s config file may be at different locations depending on your Linux distro and whether your Linux is booted in BIOS or UEFI mode. This makes regenerating Grub2 config file not easy for…
Having to go the the server room to reset servers is the most headache thing for admins managing a cluster of Linux servers in a remote site. Either you can ping the server but can not ssh to it, or you even can not ping it. There are various reasons that may cause a Linux…
The Linux kernel has a generic driver for a graphic framebuffer named vesafb on intel boxes. It provides a nice large console for most of modern displays. Setting VESA modes for Linux kernel with 32-bit and 16-bit boot protocol are different. We introduce both methods here. Linux kernel with 32-bit boot protocol For machine with…
I ever introduced [[installing-xen-domain-0-on-fedora-17]] as the first try to use the xen package delivered from Fedora and get away from manually compiling Xen and patching the kernel. In this post, I introduce installing Xen Dom0 on Fedora 20. Installing Xen First, install the xen pacakges: # yum install xen The Linux kernel is already ready…
The new development of Xen and Linux kernel make it easy to install Xen on Fedora as the Domain-0 now. This post uses Fedora 17 as an example platform to introduce how to set up Domain-0 on Fedora Linux. Compared to our old method (https://www.systutorials.com/setting-up-stable-xen-dom0-with-fedora-xen-3-4-3-with-xenified-linux-kernel-2-6-32-13-in-fedora-12/) which requires manually compiled Xen and patched kernel, the current…
Linux booting is usually controlled by Grub or the new Grub2. Setting the default booting entry is a frequent operations. Here, we introduce how to set the default entry in Grub2 and Grub. Setting the default booting entry in grub2 Note1: With some version of grub2, the grub2-set-default method and the script below may not…
The latest tools for upgrading Fedora is FedUp, please check How to upgrade Fedora 19 to Fedora 20 through the network. Please consider PreUpgrade for upgrading Fedora. This is the recommended method. This post makes a list of actions should be done to upgrade Fedora using yum. Please note that this is for experienced users…