Intel Pentium M Processor on 90nm Process with 2-MB L2 Cache Specification Update

Errata
Specification Update 35
[r/e]SP, [r/e]BP instruction. This results in a debug exception being signaled on an
unexpected instruction boundary since the MOV SS/POP SS and the following
instruction should be executed atomically.
Implication: This can result in incorrect signaling of a debug exception and possibly a mismatched
Stack Segment and Stack Pointer. If MOV SS/POP SS is not followed by a MOV
[r/e]SP, [r/e]BP, there may be a mismatched Stack Segment and Stack Pointer on any
exception. Intel has not observed this erratum with any commercially available
software, or system.
Workaround: As recommended in the IA32 Intel
®
Architecture Software Developer’s Manual, the use
of MOV SS/POP SS in conjunction with MOV [r/e]SP, [r/e]BP will avoid the failure since
the MOV [r/e]SP, [r/e]BP will not generate a floating point exception. Developers of
debug tools should be aware of the potential incorrect debug event signaling created
by this erratum.
Status: For the steppings affected, see the Summary of Tables of Changes.
X55. Corruption of CS Segment Register During RSM While Transitioning
From Real Mode
Problem: During the transition from real mode to protected mode, if an SMI (System
Management Interrupt) occurs between the MOV to CR0 that sets PE (Protection
Enable, bit 0) and the first far JMP, the subsequent RSM (Resume from
System Management Mode) may cause the lower two bits of CS segment register to
be corrupted.
Implication: The corruption of the bottom two bits of the CS segment register will have no impact
unless software explicitly examines the CS segment register between enabling
protected mode and the first far JMP. Intel® 64 and IA-32 Architectures Software
Developer’s Manual Volume 3A: System Programming Guide, Part 1, in the section
titled "Switching to Protected Mode" recommends the far JMP immediately follows the
write to CR0 to enable protected mode. Intel has not observed this erratum with any
commercially available software.
Workaround: None identified.
Status: For the steppings affected, see the Summary of Tables of Changes.