ATTN: Lexi, need some urgent info

[levicki]

Lexi,

I already asked this in virtualization section but haven't got an answer or even a hint.

What is the function of bit 3 in MSR 0x3A for Core 2 Duo mobile CPUs?

Software Developer's Manual and BIOS Writer's Guide both say that the bit is reserved but I have found code in my BIOS which is setting that bit based on some condition. I want to know what feature that bit controls.

[SHIH_K_Intel]

Quoting - Igor Levicki

Lexi,

I already asked this in virtualization section but haven't got an answer or even a hint.

What is the function of bit 3 in MSR 0x3A for Core 2 Duo mobile CPUs?

Software Developer's Manual and BIOS Writer's Guide both say that the bit is reserved but I have found code in my BIOS which is setting that bit based on some condition. I want to know what feature that bit controls.

IA32_FEATURE_CONTROL is primarily used by BIOS to pre-configure various platform features such that system executives can expect relevant hardware capability to be invariant until next boot. Bit 3 provides the BIOS pre-configuration portion of a mechanism to provide SMRAM protection. The SMRAM protection capability is provided via a pair of MSRs and is documented in Vol. 3B of the latest manual (Appendix B).

[levicki]

Quoting - Shih Kuo (Intel)

IA32_FEATURE_CONTROL is primarily used by BIOS to pre-configure various platform features such that system executives can expect relevant hardware capability to be invariant until next boot. Bit 3 provides the BIOS pre-configuration portion of a mechanism to provide SMRAM protection. The SMRAM protection capability is provided via a pair of MSRs and is documented in Vol. 3B of the latest manual (Appendix B).

Thanks, I suspected it was some additional feature. Now if I only new which SKUs support it...