Embedded Connectivity
Intel network controllers, Firmware and drivers.
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bldk & Intel SCH message Network

Community Manager


I'm tring to read PMA base haddress in order to throttle the cpu clock (Z510 / U15W) by bios.

Reference data sheet is :

Intel® System Controller Hub


(Intel® SCH)


External Design Specification (EDS)


May 2010


Revision 2.21

To issue the read on Intel Sch Message Network I'm doing:

// Intel SCH Message Network (offset 0x70 port 4)


// opcode = 0xD0 (read)


// target port = 0x04


// Reg. Address = 0x70


// Byte Enable = 0x00


pciwrite32(0, 0, 0, 0xd4, 0x00000000); // Set MDR = 0


pciwrite32(0, 0, 0, 0xd0, 0xd0047000); // Issue Read command MCR




data32 = pciread32(0, 0, 0, 0xd4);


sprintf(buffer, "HOST BRIDGE PMBA = 0x%08X\n\r", data32);





The return code is always 0x4 (data32) what's wrong?

Best Regards

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1 Reply
Valued Contributor I

Wecome to the Intel® Embedded Community.

I want to make you aware of a special place to go with questions like yours. The Intel® e-Help desk is staffed by Intel representatives who support select Intel embedded platforms including Intel Atom™ and SCH.

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If you are not already a Privileged member, you can request an upgrade to your community account here:

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I hope this helps.


J. Felix McNulty

Community Moderator (Intel contractor)