Re: xen on i7-12700

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

On Tue, Sep 03, 2024 at 09:54:24AM -0400, Greg Troxel wrote:
> [...]
> My xen install is 4.18 from pkgsrc, up to date from about a month or two
> ago, but I don't think it really changed since July.
> 
> After testing with GENERIC, I tried to boot xen.  I saw some output, and
> then the screen went black and it restarted.  It's fast and hard to
> tell, but I think it's crashing in Xen, about 1/3 of the way down the
> screen.
> 
> The CPU has 8 P cores and 4 E cores.  As I understand it, NetBSD doesn't
> understand the difference and just acts like it has 12 CPUs.  And, they
> all work, just the E cores are lower power and slower, so scheduling is
> theoretically suboptimal but I'm not sure it really matters.
> 
> I wondered if Xen was choking on E cores, so I went into the bios and
> disabled the E cores.  Xen crashed apparently the same way.
> 
> So:
> 
>   I am guessing running the debug xen might help; I'll do that next.
> 
>   Is there an easy way to tell xen to sleep 1s between each boot step,
>   so a video will capture the last output before fail?

AFAIK no. You can try to set the console synchronous with sync_console=1
on the boot line. This may require a debug kernel.

I guess there's no way to set up a serial console ?

> 
>   Does anyone have wisdom about P and E cores and Xen?

I wouldn't expect this to be a problem

> 
>   Is anyone running xen on a 12th gen intel (or 13/14)?
> 
>   Does trying to boom xen dom0 under nvmm make sense?

I never tried this. 

> 
>   Should I just try pvh?  Might as well...

I have one machine running a PVH dom0 and it's doing well. It's a:
cpu0: "Intel(R) Xeon(R) W-2223 CPU @ 3.60GHz"

For this to work you may want to disable drm

-- 
Manuel Bouyer <bouyer%antioche.eu.org@localhost>
     NetBSD: 26 ans d'experience feront toujours la difference
--