I used the Atom C2758 CPU, when wanted to read DIMM SPD info under UEFI mode, found the SMBus IO resource cleared to 0xFF(all 20h bytes IO resource), when set the SMBus controller PCI configuration register_0x4, bit0(IOSE) to 1, the IO resource still couldn't resume.
I also boot to DOS, the SMBus IO resource could be use to read DIMM SPD, but after read the SMBus controller PCI configuration register(use RU), the SMBus IO resource changed to 0xFF.
Under Windows 7, I found the bit of IOSE can change the SMBus IO resource between normal and 0xFF on real time.
I want to know, is there any switch to open the SMBus IO resource under UEFI mode?
Thank you for contacting Intel Embedded Community.
We suggest verify that your design has implemented the workarounds of erratum AVR9 and AVR30. This information can be found on pages 21 and 26 of the Intel Atom Processor C2000 Product Family Specification Update - NDA (Non Disclosure-Agreement) document # 520653. This document can be found when you are logged into your Resource & Design Center (RDC) privileged account on the following websites:
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