Intel Corp (INTC)

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Opinions? NX-bit broken on P4 J and Celeron J ?

http://www.aceshardware.com/forum?read=115105196


Celeron-J and P4-J NX-bit not functional
By Oooops on Sunday, October 10, 2004 2:49 PM EDT
Yes, the Celeron-J is now available in Japan, but Intel's erratas mention nasty bugs related to their NX-bit implementation, which will require a BIOS fix (is that some microcode updates?)

Knowingly advertising a non-functional feature is dishonest.


Edit.

http://www.intel.com/design/pentium4/specupdt/30235206.pdf

Looks like this refers to Errata R64, R65, R66, R68. Some of them do sound a bit troubling.

R65. Execute Disable Bit Set with AD Assist May Cause Livelock
Problem: If Execute Disable Bit is set and the resulting page requires the processor to set the A and/or D bit
(Access and/or Dirty bit) in the PTE, then the processor may livelock.
Implication: When this erratum occurs, the processor may livelock resulting in a system hang or operating
system failure.
Workaround: It is possible for the BIOS to contain a workaround for this erratum.
Status: For the steppings affected, see the Summary Tables of Changes.
R66. The Execute Disable Bit Fault May Be Reported before Other Types of Page
Fault When Both Occur
Problem: If the Execute Disable Bit is enabled and both the Execute Disable Bit fault and page faults occur,
the Execute Disable Bit fault will be reported prior to other types of page fault being reported.
Implication: No impact to properly written code since both types of faults will be generated but in the opposite
order.
Workaround: It is possible for the BIOS to contain a workaround for this erratum.
Status: For the steppings affected, see the Summary Tables of Changes.
R68. Execute Disable Bit Set with CR4.PAE May Cause Livelock
Problem: If the Execute Disable Bit of IA32_MISC_ENABLE is set along with PAE bit of CR4
(IA32_EFER.NXE & CR4.PAE), the processor may livelock.
Implication: When this erratum occurs, the processor may livelock resulting in a system hang or operating
system failure.
Workaround: It is possible for the BIOS to contain a workaround for this erratum.
Status: For the steppings affected, see the Summary Tables of Changes.