Published in PC Hardware

Nehalem TLB is not completely fixed

by on16 December 2008

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Hiding behind


We were pointed to this PDF here and you can clearly see that Intel tries to hide that not all of its TLB related issues have been fixed.

At page 16 of Intel Core i7 Processor Extreme Edition Series and Intel Core i7 Processor PDF, from November 2008, the company officially talks in developer language about AAJ1 erratum:

"AAJ1. MCi_Status Overflow Bit May Be Incorrectly Set on a Single Instance of a DTLB Error

Problem: A single Data Translation Look Aside Buffer (DTLB) error can incorrectly set the Overflow (bit [62]) in the MCi_Status register. A DTLB error is indicated by MCA error code (bits [15:0]) appearing as binary value, 000x 0000 0001 0100, in the MCi_Status register.

Implication: Due to this erratum, the Overflow bit in the MCi_Status register may not be an accurate indication of multiple occurrences of DTLB errors.

There is no other impact to normal processor functionality.

Workaround: None identified.

Status: For the stepping affected, see the Summary Tables of Changes."

If we follow the link to "Summary Tables of Changes" (page 10 of the same PDF) it says this:

"AAJ1 - No Fix"

As you can see, there is no fix from AAJ1 and the Nehalem and it looks that the first batch of the CPUs is affected. There is no workaround for this problem, but Intel does states that, ” There is no other impact to normal processor functionality.”

We just wanted to let you know.

Also read

Nehalem also has a TLB bug

Intel about Nehalem’s TLB errata

Last modified on 18 December 2008
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