RE: [PATCH V2 0/2] measure SMI cost (user)

[Liang, Kan]

> >
> > On Mon, May 29, 2017 at 02:52:39PM +0200, Peter Zijlstra wrote:
> > > On Mon, May 29, 2017 at 02:46:37PM +0200, Jiri Olsa wrote:
> > >
> > > > for some reason I can't get single SMI count generated, is there a
> > > > setup/bench that would provoke that?
> > >
> > > Not having SMIs is a good thing ;-)
> > >
> > > Not sure we can tickle them in a reliable way.
> >
> > yea I saw some counts last time, now just zero so I was wondering if
> > it's working
> >
> 
> We have internal test case which can generate SMI, but I cannot publish the
> test case. Sorry about that.
> 

APM_CNT (0xB2) could be used to trigger SMI#.

It's documented in PCH datasheet.
https://www.intel.com/content/dam/www/public/us/en/
documents/datasheets/9-series-chipset-pch-datasheet.pdf

APM_CNT-Advanced Power Management Control Port Register 
I/O Address: B2h 
Attribute: R/W 
Default Value: 00h 
Size: 8 bits
Lockable: No 
Usage: Legacy Only
Power Well: Core
Bit Description
7:0 Used to pass an APM command between the OS and the SMI handler. 
Writes to this port not only store data in the APMC register, 
but also generates an SMI# when the APMC_EN bit is set.

You can write a byte to port 0xB2 to trigger an SMI#

Thanks,
Kan