[Xen-devel] RE: [PATCH] clocksource=tsc

["Dan Magenheimer" <dan.magenheimer@xxxxxxxxxx>]

> > > Returning to 32-bit read_counter(), and having NULL 
> > read_counter when
> > > clocksource=tsc would be another possibility...

Well I hacked on 18055 for awhile and just couldn't get it
to boot.  I think local_time_calibration() (and thus
init_percpu_time()) is necessary for boot, though I'm not really
sure why.  Possibly the "Weirdness can happen..." comment in
that routine?

Anyway, this patch (on top of 18055) DOES work, returns to the
32-bit read_counter, and re-enables local_time_calibration().
I'd suggest putting off more major surgery for another day.

Thanks,
Dan

> -----Original Message-----
> From: Dan Magenheimer [mailto:dan.magenheimer@xxxxxxxxxx]
> Sent: Tuesday, July 15, 2008 10:04 AM
> To: dan.magenheimer@xxxxxxxxxx; Keir Fraser; Xen-Devel (E-mail)
> Cc: Dave Winchell
> Subject: RE: [PATCH] clocksource=tsc
> 
> 
> Hmmm... 18055 also fails to boot on my machine.
> 
> Could we perhaps fall back to my original patch and do
> cleanup later/separately?  I also want to try implementing
> an hpet64-based get_s_time() so will be working more
> in this code later... but want to get clocksource=tsc
> working now with minimal code impact given the freeze.
> 
> > -----Original Message-----
> > From: Dan Magenheimer [mailto:dan.magenheimer@xxxxxxxxxx]
> > Sent: Tuesday, July 15, 2008 9:46 AM
> > To: 'Keir Fraser'; 'Xen-Devel (E-mail)'
> > Cc: 'Dave Winchell'
> > Subject: RE: [PATCH] clocksource=tsc
> > 
> > > Actually in this mode of operation we hardly need a platform 
> > > timer *at all*.
> > > The idea is that we let the TSCs free-run, because we know 
> > > they will behave.
> > > Returning to 32-bit read_counter(), and having NULL 
> > read_counter when
> > > clocksource=tsc would be another possibility...
> > 
> > That's essentially what the original tscstable.patch did, though
> > I was perhaps much uglier in the miscellaneous parts.
> > 
> > Thanks,
> > Dan
> >
> 
>

Attachment: tscstable6.patch
Description: Binary data

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