1. Computers
  2. Display Drivers
  3. Graphics Cards
  4. Memory
  5. Motherboards
  6. Processors
  7. Software
  8. Storage
  9. Operating Systems


Facebook RSS Twitter Twitter Google Plus


Phoronix Test Suite

OpenBenchmarking.org

DRM Kernel Log Renderer Proposed For Linux

Linux Kernel

Published on 06 March 2014 07:35 PM EST
Written by Michael Larabel in Linux Kernel
13 Comments

One of the long-standing proclaimed benefits of Direct Rendering Manager (DRM) graphics drivers for the Linux kernel was that it would be possible to have "Blue Screen of Death"-like error messages in cases of kernel issues. That feature is now closer to being realized while also advancing another goal of disabling VT support within the Linux kernel.

David Herrmann, the open-source developer that's long been working on killing off CONFIG_VT (VT support within the Linux kernel), called for developer comments today on his DRM kernel-log renderer. Herrmann explained this work as:
On modern linux user-space, the VT subsystem is no longer needed for system consoles. Although most DEs will fail if VTs are disabled, there are several gfx-systems that support this mode. Especially the lower system stack has been extended to work without VTs.

However, there is one major drawback if VTs are disabled: You don't get oops/panic-screens nor early boot-debugging. The VT subsystem registers a console-driver, thus displays the kernel log and oops/panic screens in those situations. This patch introduces a fallback for CONFIG_VT=n.

A new DRM-Log core is added. At its heart, DRM-Log maintains a log-buffer of kernel-log messages. It registers a console-driver and pushes new messages into this buffer whenever they appear. The size of the log-buffer can be changed via drm_log_ensure_size(). Initially, a suitable buffer is chosen, but whenever drivers register high-res CRTCs, they ought to increase that buffer to guarantee there's always enough data to render the whole screen. This log-buffer is managed at the character-level, not pixel-level. It is shared across all users, supports parallel, atomic readers and writers and supports seamless resizing.

David ended his RFC message with, "With this (and the high-level integration) in place, you can easily disable CONFIG_FB, CONFIG_VT and CONFIG_FRAMEBUFFER_CONSOLE. Combined with a proper user-space system-console, you will end up with more features, less bugs and definitely some happy kernel maintainers." We'll keep watching this DRI thread to see how kernel developers accept this new DRM kernel-log renderer for pumping out kernel debug information in case of Linux system problems.

About The Author
Michael Larabel is the principal author of Phoronix.com and founded the web-site in 2004 with a focus on enriching the Linux hardware experience and being the largest web-site devoted to Linux hardware reviews, particularly for products relevant to Linux gamers and enthusiasts but also commonly reviewing servers/workstations and embedded Linux devices. Michael has written more than 10,000 articles covering the state of Linux hardware support, Linux performance, graphics hardware drivers, and other topics. Michael is also the lead developer of the Phoronix Test Suite, Phoromatic, and OpenBenchmarking.org automated testing software. He can be followed via and or contacted via .
Latest Linux Hardware Reviews
  1. AMD Radeon R9 290: Gallium3D vs. Catalyst Drivers
  2. AMD Radeon R9 290 Open-Source Driver Works, But Has A Ways To Go
  3. Trying The Configurable 45 Watt TDP With AMD's A10-7800 / A6-7400K
  4. Sumo's Omni Gets Reloaded
Latest Linux Articles
  1. 20-Way Radeon Comparison With Open-Source Graphics For Steam On Linux Gaming
  2. Preview: OS X 10.10 Yosemite vs. Ubuntu Linux GPU Performance
  3. Radeon Graphics Yield Mixed Results With Linux 3.17 Kernel
  4. AMD's RadeonSI Driver Sped Up A Lot This Summer
Latest Linux News
  1. Nouveau On Oibaf PPA Is Back To Running Well
  2. Metro 2033 Redux Will Hopefully Hit Linux Real Soon
  3. New Virtual Monitor Software Might End Up On Linux
  4. Company of Heroes 2 Might Be Coming Out For Linux
  5. NIR Still Being Discussed For Mesa, LLVM Gets Brought Up Again
  6. Plasma Active Is Mostly Ported To KDE Frameworks 5
  7. Google Chrome 37 Brings Many Security Fixes
  8. MenuetOS Updated With SMP Threads & Onscreen Keyboard
  9. Mesa Has A New Release Manager
  10. Enlightenment E19 Lands Its New Wayland Compositor Code
Latest Forum Discussions
  1. Canonical Joined The Khronos Group To Help Mir/Wayland Drivers
  2. AMD Releases UVD Video Decode Support For R600 GPUs
  3. Announcing radeontop, a tool for viewing the GPU usage
  4. Updated and Optimized Ubuntu Free Graphics Drivers
  5. [DB] BIOS - ACPI - data collecting
  6. It's Now Possible To Play Netflix Natively On Linux Without Wine Plug-Ins
  7. Users defect to Linux as OpenBSD removes Lynx from base system
  8. Chinese People Try To Patent Wine On ARM