User`s guide

15 Frequently Asked Questions
Target PC BIOS
Undesirable behavior can occur if any of the following BIOS settings are
enabled:
• Advanced Po we r Managem ent — C an cause CPU overload.
• USB ports — Can cause C PU overload.
• Plug-and-Play (PnP) operating system — Prevents PCI devices from
working properly.
• System Management Interrupts (SMIs) — Can prevent successful
operation of real-time software (cause CPU overloads).
Enabling any of these properties causes non-real-time behavior from the
target PC. You must disable these BIOS properties for the target PC to run
the target application properly in real time. See “The xPC Target Software
and the Target PC BIOS” in the xPC Target Getting Started Guide.
System Management Interrupts
To succe ssfully operate real-time software on any m icroprocessor system,
you must control and manage all interrupt services, including system
management interrupts (SMIs). However, the operating sys tem or the
application software cannot detect these interrupts.
In addition, your BIOS might not be able to disable SMIs.
For some chipsets, when you cannot disable SMIs from the BIOS, you can
programmatically prevent or disable SMIs. For example, see the Disabling
SMIs on Intel ICH5 Chipsets document at MATLAB Central for a solution to
disable SMIs in the Intel
®
ICH5 family.
Allow CPU Overloads
Typically, the xPC Target kernel halts model executio n when it encounters
a CPU ove rlo ad. You can direct the xPC Target enviro nm ent to allow CPU
overloads using the following options in the TLC options parameter in the
Real-Time Workshop pane of the Simulink Configuration P arameters dialog
box:
15-24