Disabling SMIs on Intel(R) ICH5 chipsets

Avoid CPU overloads with xPC Target(TM) on Intel(R) chipsets by disabling SMIs

Description

To successfully operate real-time software on any microprocessor system, control and management of all interrupt services is required. Unfortunately, depending on your BIOS, it may not be possible to turn off certain interrupts known as System Management Interrupts (SMIs). These interrupts are not accessible from operating system, kernel, or application software and the CPU cannot be instructed to ignore them. However, for some chipsets, such as the Intel ICH5 family, it is possible to programmatically prevent or disable the generation of SMIs.

Unexpected SMIs will cause random and spurious CPU overloads. The enclosed S-function and Simulink block will disable SMIs on the Intel ICH5 chipset family and help avoid these overloads.

• Required Products: xPC Target
• MATLAB release: MATLAB 7.5 (R2007b)

[Ian Brown]

My chipset is ICH7, and all I had to do to get this S-function to work was to add the correct PCIDevice IDs for ICH7. No more CPU Overload issues with xPC Target. (Although users of ICH7 should be aware that the ICH7 has an SMI_LOCK bit that can potentially be locked by the BIOS, which would prevent this function from working).

[Jing Huang]

Great Job! Thanks a lot.

You may add one more item in the IntelChipSets table:
{0x27B8, "945GL"},

Also, please remove S from statement printf(S, "Intel chipset not found");

Thank you very much!

[Y Mehta]

 

[Ingo Tammer]

Great job!

Your S-Function is also working for the Intel ICH9-Chipset (PCIDevice ID 0x2918)

Thank you very much!

[Ian]

For ich10, can you please add:

{0x3A14, "ICH10D0"},
{0x3A16, "ICH10R"},
{0x3A18, "ICH10"},
{0x3A1A, "ICH10D"},

[Michael]

This S-function worked for a Core 2 Duo (ICH7). I also have a Core i7 and a Xeon machine that both seem to be suffering from the same CPU Overload problems. I added the Device ID for the ISA Bridge (under PCI devices in xpcexplr) to the S-fuction code since that seemed to be what was done to add support for the other chipsets. For both the Xeon and Core i7, it seems to find the chipset, but gives me the following error: "Failed to Clear GBL_SMI_EN bit; SMI_LOCK may be set" Any suggestions?

[Chris]

Added {0x2914, "ICH9D0"} and my SMI problems disappeared. The module also appears to prevent long TETs arising from enabled USB support (useful if one also uses the target machine for Windows and/or has a motherboard lacking PS/2 support).