RE: [Xen-devel] "Time went backwards" messages

["Ian Pratt" <m+Ian.Pratt@xxxxxxxxxxxx>]

> I have a high end IBM system with 4 HT CPUs, am running 
> xen-unstable with only Dom0 active, and I get lots of "Timer 
> ISR/n: Time went backwards" messages.  This is a short 
> segment from dmesg:

> The system has a Cyclone timer, and I am looking at using the 
> Cyclone timer to avoid the TSC drift, but while it is easy to 
> add to xen, all the cyclone support has been removed from linux.  

TSC drift? Are all the CPUs not running off the same bus clock on this
system?

It sounds like Xen just really isn't happy on this platform. If you look
at the Xen boot messages ('xm dmesg') does it look like it's identified
the CPU frequecies and local APIC (bus) clock correctly?

ian

> I have some prototype cyclone code added to xen, but have not 
> done anything to Linux yet.
> 
> --
> Don Fry
> brazilnut@xxxxxxxxxx
> 
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> 

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