Knowledge Base

READ_REGISTER_ULONG Doesn't Preserve ULONG Semantics on Alpha

Article ID: 160610

Article Last Modified on 11/1/2006

APPLIES TO

This article was previously published under Q160610

SYMPTOMS

The READ_REGISTER_ULONG routine in the HAL for Alpha platform computers does not preserve the ULONG semantics, which may cause the computer to stop responding or bugcheck.

CAUSE

Currently, the READ_REGISTER_ULONG routing explicitly zeros out the upper four bytes of the return value. This will destroy ULONG semantics, where bit 31 is sign extended through to bit 63. This will potentially cause drivers that poke memory mapped I/O for expected signatures to fail when comparing the return value of READ_REGISTER_ULONG to a static constant when bit 31 of the constant is set.

STATUS

Microsoft has confirmed this to be a problem in Microsoft Windows NT version 4.0.
This problem was corrected in the latest Microsoft Windows NT 4.0 U.S. Service Pack. For information on obtaining the service pack, query on the following word in the Microsoft Knowledge Base (without the spaces):

S E R V P A C K


Additional query words: prodnt alpha

Keywords: kbhardware KB160610


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