Re: [Xen-devel] Latest development (master) Xen fails to boot on HP ProLiant DL20 GEN10

[Roman Shaposhnik <roman@xxxxxxxxxx>]

On Thu, Sep 26, 2019 at 12:44 AM Jan Beulich <jbeulich@xxxxxxxx> wrote:
>
> On 26.09.2019 00:31, Roman Shaposhnik wrote:
> > Jan, Roger, thank you so much for the initial ideas. I tried a few of
> > those and here's where I am.
> >
> > First of all, it is definitely related to CPU bring up. Adding
> > cpuidle=0 to xen command line made Xen boot.
> >
> > Then, a good friend of mine (who you may know from ancient Xen days
> > ;-)) suggested that this could be related to this:
> >      https://wiki.xenproject.org/wiki/Xen_power_management
> > so I went to the BIOS settings and quite to my surprise all of them
> > were grayed out (not tweakable).
> >
> > The only one that wasn't was 2xAPIC support. So just for kicks -- I
> > disabled that.
> >
> > That, in turn, made Xen boot even without cpuidle=0. I'm attaching that log.
>
> Interesting, but unfortunately this particular log is of no real use
> for investigation of the issue (other than knowing the CPU model). I
> also notice it's a 4.12.0 log, when your original report was against
> latest master.
>
> > So I guess at this point, you could say that I have a functional
> > system, but I'm curious whether you guys would be interested to look
> > into 2xAPIC situation.
>
> Of course we do. As a next step I'd suggest reverting the BIOS settings
> change you did, and instead using the "x2apic=0" Xen command line option.

Interestingly enough, this doesn't really solve the problem completely.
Specifying x2apic=0 certainly makes Xen go much further to a point
where it tries to load Dom0 and then the console VGA screen goes
blank (this is where that serial debug output would be very useful :-().

I suppose I can buy:
     
https://www.cdw.com/product/hpe-dl20-ml30-gen10-m.2-dedicated-ilo-and-serial-port-kit/5348024
but that'll take some time to arrive.

> And then we of course need a complete boot log (as requested earlier) of
> a problem case.
>
> Further I'd suggest moving away from the black-and-white "cpuidle="
> option, and instead limiting use of deep C states ("max_cstate="). I
> wouldn't be surprised if this was the issue; we'd then have to first
> of all go through errata for the part your system is using.

Yup. max_cstate=1 makes it boot fine. max_cstate=2 though hangs
the system *exactly* in the same way as specifying x2apic=0
(which is different from the original problem as I've described above).

Can you please elaborate on "we'd then have to first of all go through
errata for the part your system is using"

Thanks,
Roman.

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/mailman/listinfo/xen-devel