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Chapter 1. Kernel

The kernel shipped in Red Hat Enterprise Linux 6.5 includes several hundred bug fixes for, and enhancements to the Linux kernel. For details concerning important bugs fixed and enhancements added to the kernel for this release, refer to the kernel section of the Red Hat Enterprise Linux 6.5 Technical Notes.

Support for PMC-Sierra Cards and Controllers

The pm8001/pm80xx driver adds support for PMC-Sierra Adaptec Series 6H and 7H SAS/SATA HBA cards as well as PMC Sierra 8081, 8088, and 8089 chip based SAS/SATA controllers.

Configurable Timeout for Unresponsive Devices

In certain storage configurations (for example, configurations with many LUNs), the SCSI error handling code can spend a large amount of time issuing commands such as TEST UNIT READY to unresponsive storage devices. A new sysfs parameter, eh_timeout, has been added to the SCSI device object, which allows configuration of the timeout value for TEST UNIT READY and REQUEST SENSE commands used by the SCSI error handling code. This decreases the amount of time spent checking these unresponsive devices. The default value of eh_timeout is 10 seconds, which was the timeout value used prior to adding this functionality.

Configuration of Maximum Time for Error Recovery

A new sysfs parameter eh_deadline has been added to the SCSI host object, which enables configuring the maximum amount of time that the SCSI error handling will attempt to perform error recovery, before giving up and resetting the entire host bus adapter (HBA). The value of this parameter is specified in seconds, and the default is zero, which disables the time limit and allows all of the error recovery to take place. In addition to using sysfs, a default value can be set for all SCSI HBAs using the eh_deadline kernel parameter.

Lenovo X220 Touchscreen Support

Red Hat Enterprise Linux 6.5 now supports Lenovo X220 touchscreen.

New Supported Compression Formats for makedumpfile

In Red Hat Enterprise Linux 6.5, the makedumpfile utility supports the LZO and snappy compression formats. Using these compression formats instead of the zlib format is quicker, in particular when compressing data with randomized content.