I found a way to disable SMI. Furthermore, I found that TCO_EN bit is causing SMI#. I am using Intel 82801DB ICH4.
How safe it is to disable SMIs? Is there any problem with overheating of CPU or any other side effect?
Thanks,
Slavisa Zigic In comp.realtime Slavisa Zigic wrote: : I also have a real-time app that runs on P4. It is running on AAEON MB-845GE : motherboard. CPU stalls for 250us for unknown reason. This event is not : periodic, sometimes it is after less than a minute, sometimes you have to : wait for few minutes. Motherboard is using Intel 845GE chipset. I downloaded : datasheet for South Bridge and wrote small program to read SMI enable : registers. All values are default (as specified in datasheet), that is, SMI : disabled. : After that, I disabled Thermal Monitor on CPU (TM1 & TM2) by writing to MSR : IA32_MISC_ENABLE (bits 3 and 13). No change. Still have 250us stall.
: 'cli' did not help, disabling APIC didn't help, disabling ALL interrupts on : PIC didn't help, writing to Intel Software Developers Forum didn't help...
: Slavisa Zigic
: In comp.realtime snipped-for-privacy@gmail.com wrote: : : Armin Steinhoff wrote: : :> snipped-for-privacy@gmail.com wrote: : :> > I have a real-time app that runs on a P4. The box we are running it on : :> > has an Aopen i865PEa-7IF motherboard. We are using the On-Time RTOS. : :> > We have found that every 37 seconds the app completely stops running : :> > for 250 microseconds. Using a PCI bus analyzer we discovered that : :> > between the last operation done by my app and when my app resumes : :> > running shows 100's and 100's of I/O reads and writes to addresses B3, : :> > EB, and 61. Googling on this has led me to believe that these accesses : :> > are related to SMI's and SMM. I have disabled everything in the BIOS - : :> > USB, LAN, power management, serial and parallel ports, modem, firewire, : :> > MIDI and game ports - yet my app still stops and I still see these : :> > accesses. : :> >
: :> > Does anyone know how I can totally disable the SMI's? : :>
: :>
formatting link
: :>
formatting link
snipped-for-privacy@gna.org/msg01507.html
: : The code at this link is for the AMD Geode GX-1. It is not applicable : : to the P4.
: : -larry