What version of Red Hat Enterprise Linux is required to support Intel processors with greater than 36-bit physical addressing?

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When running in 64-bit mode, Intel® Xeon® processors that support greater than 36-bit physical addressing require Red Hat Enterprise Linux 4 Update 6 or Update 5 errata kernel-2.6.9-55-0.12, updated after November 1st, 2007, or Red Hat Enterprise Linux 5 for support. Failure to implement these minimum Red Hat Enterprise Linux versions may lead to serious system errors. These CPUs include the Dual-Core Intel® Xeon® 5100 Series processor (codenamed "Woodcrest", G-0 stepping), Quad-Core Intel® Xeon® 5300 Series processor (codenamed "Clovertown", G-0 stepping), the Quad-Core Intel® Xeon® 5400 processor (codenamed "Harpertown") and the soon to be released processor codenamed "Wolfdale-DP", all of which support 38-bit physical addressing. Previous CPU steppings of the Intel® Xeon® 5100 and 5300 series which support 36-bit physical addressing do not require these updates.

To determine if a processor has greater than 36-bit physical addressing, issue the command cat /proc/cpuinfo and look for the physical address size reported on the line that begins with 'address sizes'. Here is an example from a system with greater than 36-bit physical addressing:

address sizes   : 38 bits physical, 48 bits virtual

Remember, the updated kernels are only needed for 64-bit Red Hat Enterprise Linux. The 32-bit version works correctly with these processors.