Re: [PATCH][2.6.7-mm1] perfctr ppc32 update

[Mikael Pettersson <mikpe@csd.uu.se>]

Benjamin Herrenschmidt writes:
 > On Tue, 2004-06-22 at 15:09, Mikael Pettersson wrote:
 > > Benjamin Herrenschmidt writes:
 > >  > Hrm... your code will not work with externally clocked timebases
 > >  > (like the G5) and I'm not sure you get the core freq. right with
 > >  > CPU that can do clock slewing or machines that can switch the
 > >  > core/bus ratio (laptops).
 > > 
 > > Do you mean the PLL_CFG code that's been in -mm for the last couple
 > > of weeks, or just the recently posted update? The update replaced
 > > in-kernel /proc/cpuinfo parsing (gross) with OF queries taken straight
 > > from the pmac code in arch/ppc/platform/.
 > > 
 > > I'm ignoring 970/G5 until IBM releases the damn documentation.
 > 
 > Well, the G5 can have it's own tb but can also be externally clocked and
 > that's how Apple does. I'm not sure about all G4 models.

So what you're saying is that PLL_CFG may not reflect the true
relationship between the TB frequency and the core frequency?

That shouldn't be a problem as long as there's _some_ in-kernel
interface for finding that out. If querying OF isn't the correct
approach, then what is?

/Mikael