smb driver for Nvidia ION (intel ATOM) chipset

Jeremy Chadwick freebsd at
Thu Jan 7 08:05:12 UTC 2010

On Thu, Jan 07, 2010 at 08:48:05AM +0100, Oliver Lehmann wrote:
> Re: smb driver for Nvidia ION (intel ATOM) chipset writes:
> >It's easy to get confused by the state of hardware monitoring on not
> >only FreeBSD but other OSes as well; they all make it sound like
> >monitoring things "just magically works with SMBus", and that isn't the
> This is what I was thinking so far - yeah exactly ;)
> I'v now went deeper into mbmon's source and found that stuff out
> sorta...
> Looks like I've to do some more research what really is on my board
> first.
> Using the ISA-IO access method mbmon thinks I've a LM78 and mbmon
> even works but I'm getting false numbers for probably just
> everything...
> root at nudel xmbmon205> mbmon
> Temp.= 185.0,  0.0,  0.0; Rot.=  835, 30681, 18750
> Vcore = 1.10, 1.81; Volt. = 3.39, 4.95,  8.21,  -7.51, -3.24
> ^C

This is the exact sort of situation I was referring to -- at this point
your system may be unstable.  The mbmon software has initiated a raw LPC
(ISA) I/O request on a port which obviously is not tied to an LM78 H/W
monitoring IC.  Who knows what all of the writes and reads to those
offsets just did.

I would recommend you reboot and/or power cycle this box ASAP given the
nature of what transpired.  One has to be very careful when operating
with /dev/io that the proper (LPC/ISA) ports are used.  The same applies
to most bus architectures (SMBus, PCI, etc.), though in the case of PCI,
there's existing infrastructure to find out what's on the bus properly.
There isn't such with SMBus and LPC/ISA.

Now you see why I strongly discourage auto probing.  :-)

> root at nudel xmbmon205> mbmon -d
> SMBus[NVidia nForce2] found, but No HWM available on it!!
> Using ISA-IO access method!!
> * Nat.Semi.Con. Chip LM78 found.
> root at nudel xmbmon205>

Yeah, this looks like a very bad assumption made by the software.

You're very likely going to have to end up mailing the board
manufacturer/vendor and asking them -- that is, assuming there's a H/W
monitoring IC on the board at all.

If you have access to Windows 2K/XP, you might try using some software
there called SpeedFan.  If it works, you'll be able to at least figure
out what H/W monitoring IC is used, and if it's via SMBus or LPC/ISA.
What registers, slave address, etc. it uses are a different matter
altogether (I'm not sure the software discloses that).

| Jeremy Chadwick                                   jdc at |
| Parodius Networking              |
| UNIX Systems Administrator                  Mountain View, CA, USA |
| Making life hard for others since 1977.              PGP: 4BD6C0CB |

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