Re: IO-APIC on nforce2 [PATCH] + [PATCH] for nmi_debug=1 + [PATCH] for idle=C1halt, 2.6.5

[Craig Bradney <cbradney@zip.com.au>]

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On Thu, 2004-04-29 at 13:44, Ross Dickson wrote:
> On Thursday 29 April 2004 06:59, Jesse Allen wrote:
> > On Wed, Apr 28, 2004 at 09:33:34PM +1000, Ross Dickson wrote:
> > > > 
> > > > It may be this board never hangs no matter what,
> > > > or perhaps C1 disconnect was simply disabled in that BIOS
> > > > b/c there was no option for it in Advanced Chipset Features
> > > > like there is for the most recent BIOS.
> > > 
> > > Maybe other MOBO manufacturers skimp on filter caps and regulator damping
> > > ability and a resonance occurs in the on-board supply rails? Do Shuttle make
> > > any claims to using an improved on board regulator? Or Shuttle may have 
> > > always programmed more time in C1 cycle handshakes if such is 
> > > configurable? 
> > 
> > Do you really think so?  I think there may be a resonance occuring, even with 
> > this new BIOS.  I plugged in new headphones into my nforce2 onboard sound, and 
> > get a high pitched noise.  Now here is where it gets weird:  This noise does 
> > not occur on boot until sometime after the IDE driver is loaded.  I also 
> > believe it varies under a high load.  If you disable C1 disconnect, it's gone.  
> > Also I've heard a high pitched noise at certain times coming right from the 
> > copmuter (very faint, but I do have very good hearing, I can even hear a hush 
> > sounding from my router.  my brother was quite astonished when I pointed that 
> > out)  I try to distinguish whats doing it.  It could be the hard drive.  But 
> > when I found the other sound in the head phones, I found that the sound varies 
> > almost in unison with the sound coming from the computer.  Maybe the IDE or 
> > hard drive is related, but it is too much related to C1 disconnect.
> 
> I think I might break out my oscilloscope this weekend and have a look at how 
> clean the supply rails are around the cpu and northbridge and southbridge. 
> Who knows I might get lucky and see some unexpected ripple or spikes.
> 
> > 
> > Whether it is really possible that my board can really generate this sound, I 
> > don't know.  Though, I have once determined that resonance was occuring in an 
> > old system, causing unstable CPU operation.  It wasn't that I heard a sound 
> > coming from it =).  But what I thought was the case was causing it, and pulled 
> > it out of the case.  I ran it on the table and found it to be stable.  That 
> > was the only thing wrong.  I've also studied resonance before a bit.  I know 
> > resonance can break systems.  But to think that my board is doing emmitting 
> > noise like that is pretty bizarre.
> 
> Not as bizarre as you may think. I have heard coils and even capacitors "sing"
> in years past whilst servicing electronics.
> 
> > 
> > It may be true that this Shuttle board may have resonance problems.  So that 
> > would indicate that they did something much like you describe by changing the 
> > C1 handshake time?  Isn't that much like what your patch does?
> 
> I had not really thought about it from that perspective. Whilst my patch cannot 
> alter the handshake times it does prevent consecutive C1 cycles from occurring
> too close together. Too close together I think being less than about 800ns. I 
> guess I could look at that with a cro too - use an appropriate pin as the trigger
> source and see if supply rails have load dump voltage rises when going into
> disconnect. Maybe rail voltage rings for about 700ns and might be out of 
> tolerence inside Athlon during that time. Would be very interesting if a 
> few hundred picofarad of low esr decoupling cap placed on a supply rail near a
> chip makes a difference? A pinout of the nforce2 chipset would help a great deal
> here but I do not have one. Can anyone oblige me?
> 
> > 
> > 
> > > 
> > > > hang issue is completely explained and solved.
> > > 
> > > I have had good (100%) success in reproducing the fault with the Albatron 
> > > KM18G pro MOBO. I needed m-atx form factor and distributor was local to me.
> > > Makes very nice - cheap and stable system but only with the lockup workaround.
> > > 
> > > I also recollect that Windows had lockups with nforce2 for a while depending 
> > > whether you ran the Nvidia or Microsoft driver.
> > > http://lkml.org/lkml/2003/12/13/5
> > > Anybody got the inside running on that one and what was different between the 
> > > two drivers?
> > > 
> > 
> > Yeah, unfortunately, I didn't save a link to the message board that I found 
> > that on.  But the issue is pretty common.  I'm sure more info can be found on i
> > the windows side.
> 
> No tech info but this link shows user had Lockups with Nvidia's ide driver but
> OK with MS one.
> http://club.cdfreaks.com/showthread/t-91381.html
> 
> -

This has become a rather interesting problem to watch from afar. The
Athlon here seems to have no issues with the NForce driver under Windows
(I dont burn a lot of DVDs on it tho). Whenever its in Linux, its mainly
a testing machine these days.

It will be interesting to see if theres a real hardware problem and then
if it can be worked around in software (cant image a single product
recall happening).

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