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,…
Most time, we need to tune system parameters to achieve better performance but what the general parameters to be tuned in Linux systems. I think you may want to add following parameters to Kernel boot (/etc/default/grub) parameters intel_idle.max_cstate=0 processor.max_cstate=0 idle=poll intel_pstate=disable At the same time, you may also want to shutdown/open Pause Loop Exiting (PLE)….
If we want to change the tick time for Linux Kernel, we need to change CONFIG_HZ parameter in Linux Kernel. Do we have other better ways to change it rather than compiling Linux Kernel. Please ignore the way to add ‘divider=10’ in grub config file because it is limited only for RH/CentOS distros. Zhiqiang, please…
My Ubuntu boots to GUI mode by default. How to make Ubuntu Linux boot to text mode? If you are using Ubuntu older than 16 such as Ubuntu 14.04: Edit /etc/default/grub Change GRUB_CMDLINE_LINUX=… to GRUB_CMDLINE_LINUX=”text”. Backup your old grub config`$ sudo cp -n /etc/default/grub /etc/default/grub.bak-date +%s ` Update grub$ sudo update-grub If you are using…
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…
Grub fails to boot with Windows 8 UEFI after installing Fedora 20. The Grub entry for Windows 8 is: menuentry ‘Windows Boot Manager’ { chainloader /EFI/Microsoft/Boot/bootmgfw.efi boot } How to fix it? The set root= is missing. You probably can fix this by specifying the root manually: menuentry ‘Windows Boot Manager’ { insmod part_gpt set…
Installing Fedora 19, Error “you have not created a bootloader stage1 target device” . It seems appear from Fedora 15: http://forums.fedoraforum.org/showthread.php?t=271743 This can be solved by adding noefi nogpt to the kernel parameters when booting the Linux for installation in grub as follows. Note: the “_” between nogpt and root is the cursor, not the…
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 Linux disk names (e.g. sda1, hdb3, etc.) are not reliable—they may be changed if there are hardware changes, such an adding or removing a disk. Additionally, the order for the Linux device names is not always the same as the order of SATA poets. For example, the disk connected to SATA port 0 (first…
The performance of Xen’s Dom0 is important for the overall system. The disk and network drivers are running on Dom0. I/O intensive guests’ workloads may consume lots Dom0′s CPU cycles. The Linux kernel calculates various network related parameters based on the amount of memory at boot time. The kernel also allocate memory for storing memory…
If /etc/fstab file is created with errors or the hardware configuration changes such as adding hard disks, Linux will boot into failure state. We can bypass the fstab failure by adding booting parameters to Linux. We can do this in two methods: Method 1: Boot to single user mode When booting into single user mode,…
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…