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04 April 2012, 16:51

Kernel Log: Intel hibernate bug fixed

by Thorsten Leemhuis

New versions of the Linux kernel fix a bug in Intel graphics drivers which could cause memory corruption. AMD has released X.Org drivers for its new Trinity processors. In September there will be a conference for X developers in Nuremberg. Progress has been made on GPGPU support in Mesa 3D.

Kernel versions 3.0.27, 3.2.14 and 3.3.1 were released on Monday evening and should resolve the bug which resulted in occasional memory corruption when systems with Intel graphics were woken from sleep (hibernation/software suspend/Suspend to Disk/ACPI S4). This fix has already been merged into the first pre-release version of Linux 3.4, which was released over the weekend.

The problem lies in the i915 DRM/KMS driver and has been present for at least a year. Most Intel notebook and desktop chipsets and processors released in the last five to seven years appear to be affected by the bug. As the commit comments on the fix reveal, the code for blinking the cursor in the console was at fault. This code now deactivates the function responsible for blinking the cursor when switching into and out of hibernation – Radeon and Nouveau DRM/KMS drivers have long taken this approach.

The release messages for the new stable and long-term kernels include a firm recommendation that users switch to one of the new versions. This is a standard message, as the kernel developers do not examine whether the enhancements and bug fixes might include fixes which plug security vulnerabilities. Users who do not compile their own kernels can, however, ignore this recommendation, since, as long as the distribution they are using is still being maintained, distributors should take care of providing kernel updates for remedying critical bugs. In the case of the i915 DRM/KMS driver, many distributors are likely to take such steps, since this bug can result in data corruption in various forms.

New Radeon drivers

AMD developer Alex Deucher has released xf86-video-ati 6.14.4, a new X.Org Radeon driver package that adds support for the graphics cores in AMD's Trinity CPUs, which are due to be released in the coming months. The driver is, however, dependent on DRM/KMS support for Trinity in the kernel in order to address the Aruba, aka R9xx, graphics core. Support for this was announced two weeks ago and merged into the Linux mainline shortly thereafter. Together with libdrm 2.4.33 and the Mesa 3D developer tree, this should enable the graphics core (a member of the "Northern Islands" family) to employ 3D acceleration. The new Radeon driver for X.Org's X Server also adds support for 2D tiling for Evergreen and Northern Islands GPUs, which can improve graphics performance. This feature also requires support in the DRM/KMS driver, merged in Linux 3.4.

In late March, AMD released version 12.3 of its proprietary Catalyst/Fglrx graphics driver. As usual, the company has yet to provide any information on the changes made. Like its predecessor, it is still not compatible with X Server 1.12, which was released a month ago.

Next: In brief - kernel, graphics

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