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,
Read more
Tag: Grub
How to tune systems to achieve high performance in virtualization circumstances?
Posted onMost 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).
Read more
How to change CONFIG_HZ parameter for Linux Kernel
Posted onIf 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
Read more
How to make Ubuntu Linux boot to text mode?
Posted onMy 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
Read more
How to Add “nomodeset” to Grub2 in Fedora and Ubuntu
Posted onI 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.
Read more
How to make Linux automatically reboot after a kernel panic?
Posted onAfter 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,
Read more
How to boot Linux Mint to the console by default?
Posted onHow 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
Read more
Fix the Grub issue with Windows 8 UEFI after installing Fedora 20
Posted onGrub 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
Read more
Installing Fedora 19, Error “you have not created a bootloader stage1 target device”
Posted onInstalling 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
Read more
Grub2: How to boot Fedora to an old kernel?
Posted onGrub2: 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
Read more
Building and Installing Linux Kernel from the Source Code in an Existing Linux OS
Posted onBuilding 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
Read more
How to Regenerate Grub2 Config Files on Linux
Posted onGrub2 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
Read more
Lazy Linux Admins Going to Server Rooms Less: Forced Reboot, Auto Reboot after Kernel Panic and Email Notification after Reboot
Posted onHaving 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
Read more
How to Configure Linux Kernel Video Mode for 32-bit and 16-bit Boot Protocols
Posted onThe 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
Read more
Installing Xen on Fedora 20 as Domain-0
Posted onI 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
Read more
How to Find Out Failed Disks’ SATA Ports in Linux
Posted onThe 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
Read more
Managing Xen Dom0′s CPU and Memory
Posted onThe 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
Read more
How to Bypass Bad fstab Failure When Booting Linux
Posted onIf /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,
Read more
How to Install Xen on Fedora as Domain-0 (Fedora 17)
Posted onThe 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
Read more
How to Set Default Entry in Grub2 and Grub
Posted onLinux 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
Read more