Re: [Xen-devel] dom0less + sched=null => broken in staging

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Tue, 13 Aug 2019, Dario Faggioli wrote:
> On Fri, 2019-08-09 at 11:30 -0700, Stefano Stabellini wrote:
> > On Fri, 9 Aug 2019, Dario Faggioli wrote:
> > > Can you help me with this, e.g., by providing some more info and,
> > > if
> > > possible, logs?
> > 
> > I am attaching the logs. 
> >
> Thanks!
> 
> > Interestingly, I get a bunch of:
> > 
> > (XEN) *** LOADING DOMU cpus=1 memory=40000KB ***
> > (XEN) sched_null.c:458: Not inserting d2v0 (not online!)
> > 
> > Maybe we are missing a call to online the vcpus somewhere in
> > xen/arch/arm/domain_build.c:construct_domain?
> > 
> Actually, those lines are normal, because vCPUs are created offline.
> (see the set_bit(_VPF_down) in vcpu_create()).
> 
> The problem is why aren't they coming up. Basically, you're missing a
> call to vcpu_wake().
> 
> In my (x86 and "dom0full") testbox, this seems to come from
> domain_unpause_by_systemcontroller(dom0) called by
> xen/arch/x86/setup.c:init_done(), at the very end of __start_xen().
> 
> I don't know if domain construction in an ARM dom0less system works
> similarly, though. What we want, is someone calling either vcpu_wake()
> or vcpu_unpause(), after having cleared _VPF_down from pause_flags.
> 
> I am attaching an updated debug patch, with an additional printk when
> we reach the point, within the null scheduler, when the vcpu would wake
> up (to check whether the problem is that we never reach that point, or
> something else).

See attached.

Attachment: konsole.txt
Description: Text document

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