3. Kernel
3.1. Kernel Platform Enablement
This release introduces support for Intel's new platforms, code-named
Boxboro-EX and Boxboro-MC, AMD's new processor family, code-named Magny-Cours and IBM's Power7 processor.
3.2. Kernel Generic Features
The recommended minimal memory requirement on x86 and x86_64 for Red Hat Enterprise Linux 5.5 is now 1GB per logical CPU.
Note
A logical CPU is defined as any entity that can be scheduled (i.e. every core or thread in a multi-core or multi-thread processor is defined as a logical CPU).
Detecting kernel tasks stuck in the uninterruptible sleep state
In some circumstances, tasks in the kernel may permanently enter the uninterruptible sleep state (D-State), making the system impossible to shut down. With this update, the Detect Hung Task kernel thread has been added, providing the ability to detect tasks permanently stuck in the D-State.
This new feature is controlled by the
CONFIG_DETECT_HUNG_TASK kernel flag. When set to "y" tasks stuck in the D-State are detected; when set to n it is off. The default value for the CONFIG_DETECT_HUNG_TASK flag is y.
Additionally, the
CONFIG_BOOTPARAM_HUNG_TASK_PANIC flag has been added. When set to y, a kernel panic is triggered when a task stuck in the D-State is detected. The default value for the CONFIG_BOOTPARAM_HUNG_TASK_PANIC flag is n.
Signed s390 Kernel Modules
Starting at Red Hat Enterprise Linux 5.5, all s390 kernel modules are now signed. BZ#483665
