Linux kernel 4.19.70 is a stable release containing 95 fixes and improvements across multiple subsystems. This release addresses critical issues in audio, networking, storage, virtualization, DMA handling, and various device drivers. Major Fixes Audio and Sound ALSA USB Audio Improvements The release includes several USB audio enhancements. A quirk was added for Behringer UFX1604 to…
Storage Limitations BIOS uses MBR (Master Boot Record) partitioning, which maxes out at 2.2TB addressable space due to 32-bit LBA limitations. UEFI uses GPT (GUID Partition Table), supporting drives up to 9.4 zettabytes theoretically—practically unlimited for current hardware. If you’re deploying systems with large storage arrays or NVMe drives, UEFI is mandatory. Boot Process UEFI…
The simplest way to detect whether your Linux system booted in UEFI or BIOS (Legacy) mode is to check for the existence of the EFI firmware directory. Check for EFI Directory The /sys/firmware/efi/ directory only exists when the system has booted in UEFI mode. If it’s absent, the system is running in BIOS/Legacy mode. […
While BIOS settings are the preferred way to disable USB 3.0, you can also force USB 2.0 mode on a running Linux system by manipulating the xHCI controller’s port routing register directly using setpci. How it works Intel xHCI controllers use the XUSB2PR (xHC USB 2.0 Port Routing Register) at offset 0xd0. Setting this register…
Managing display power and screen blanking on Linux systems is essential for reducing power consumption on servers, headless machines, and workstations. Two primary tools handle this: setterm for software-based blanking and vbetool for hardware power management via VESA DPMS. Screen Blanking with setterm The setterm command controls when and how the console screen blanks during…
If you installed Linux in BIOS (Legacy) mode but need to boot alongside Windows in UEFI mode, converting an existing installation is possible but complex. This guide covers the process for modern systems while preserving your existing Linux installation and Windows setup. Before starting: Back up your data. This procedure involves disk partitioning and bootloader…
The Completely Fair Scheduler (CFS) is the default process scheduler in Linux kernels since 2.6.23. It allocates CPU time proportionally based on process priority, but the actual timeslices and preemption behavior depend on three key tunable parameters: sched_latency_ns, sched_min_granularity_ns, and sched_wakeup_granularity_ns. Understanding how these work together is essential for tuning scheduler behavior on production systems….
When you repurpose disks from one RAID array to another system, Linux keeps the old RAID metadata intact as a safety measure. This prevents accidental data corruption, but it also blocks you from reusing the disk until the signatures are cleared. RAID metadata isn’t stored in one place — it’s scattered across the disk by…
GRUB2 configuration needs to be regenerated when you modify boot parameters, install new kernels, or adjust default boot entries. The process varies slightly between BIOS and UEFI systems, and between distributions, but follows a consistent pattern once you understand your system layout. Check Your System Firmware Type Before regenerating config, identify whether your system uses…
The Linux kernel handles video mode configuration through bootloader parameters and kernel graphics drivers. Modern UEFI systems use Kernel Mode Setting (KMS) automatically, but you can override modes when needed. Legacy BIOS systems still use older mechanisms if you’re maintaining older hardware. UEFI Systems: Modern Video Mode Configuration On UEFI systems with GRUB2, add video…
RAID0 (striping) on enterprise RAID controllers like Broadcom MegaRAID is used to expose multiple disks as a single logical volume with no redundancy. This configuration is appropriate only for performance-critical workloads where data loss from a single disk failure is acceptable, or for temporary/cache storage. This guide covers the full setup process on servers with…
A failed BIOS flash can leave your HP Compaq laptop completely unresponsive — white screen, no boot, just LED blinking. Before declaring it dead, try HP’s built-in crisis recovery mechanism. This procedure has recovered many laptops that appeared permanently bricked. The process works even when CMOS corruption prevents normal startup. You’ll need a USB flash…
Modern Linux systems use GRUB2 as the bootloader. You’ll set the default boot entry either through the configuration file or via command-line tools. View Available Boot Entries First, list all available GRUB2 menu entries: grep ^menuentry /etc/grub2.cfg | cut -d “‘” -f2 On UEFI systems, use /etc/grub2-efi.cfg instead. If you’re unsure which mode your system…
The firmware (BIOS/UEFI) on your system contains critical hardware settings and boot information. Knowing your firmware version is essential for updates, compatibility checks, and troubleshooting. Here’s how to find it. Using dmidecode dmidecode is the standard tool for reading the Desktop Management Interface (DMI) table, which stores hardware and firmware metadata. Most distributions include it,…
Xen remains relevant in production environments (AWS EC2, Citrix Hypervisor), though KVM has become the default for most Linux distributions. This guide covers frequent installation and configuration issues specific to Fedora Dom0 setups, with many tips applicable to other Linux platforms. BIOS Configuration If Xen fails with “I/O virtualization disabled,” you need to enable virtualization…
Free virtualization on Linux has multiple solid options. While VMware Player is still available, QEMU combined with libvirt has become the standard approach for most sysadmins. This guide covers creating VM disk images and configurations that work across multiple hypervisors. Creating Virtual Disk Images The first step is creating a virtual disk. QEMU’s qemu-img tool…