Re: [Xenomai] Problems disabling SMI interrupts on MSI H87-G43 motherboard

[Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>]

On Thu, Oct 08, 2015 at 11:08:46AM +0200, Jeroen Van den Keybus wrote:
> >> >> Thanks everybody, seems like I have to give up on that motherboard:
> >> >>
> >> >> 1. Nothing found to disable in the BIOS
> >> >> 2. Disabling all sourcecs with smictrl
> >> >(git://git.kiszka.org/smictrl.git)
> >> >>    still gives high latencies with RTNet (+1.5 milliseconds).
> >> >> 3. latency test does not show anything suspicious, so it might
> >> >>    be some other issue.
> >> >>
> >> >> Anybody that has a suggestion on a recent motherboard that has been
> >> >used with
> >> >> RTNet and showing good results?
> 
> As you found out, most MB BIOSes set the SMI lock bit. No way around it.

According to the documentation the SMI lock bit should only lock the
SMI_EN register bit 0, that is the "global disable" bit. However, on
the last machines where I had SMI issues, the SMI_EN register was
entirely read-only, so there must be other ways than the SMI lock
bit to lock the SMI_EN register, which is why smi.c write then reads
the register, instead of checking the SMI lock bit.

-- 
					    Gilles.
https://click-hack.org