Re: [Xen-devel] [BUG] Serial port prevents PVH dom0 boot

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Thu, Jul 26, 2018 at 09:08:08AM -0400, Connor Davis wrote:
> 
> On July 26, 2018 4:03 AM, Roger Pau Monné <roger.pau@xxxxxxxxxx> wrote:
> 
> > On Wed, Jul 25, 2018 at 04:10:59PM -0400, Connor Davis wrote:
> >
> > > When booting into dom0=pvh, using the serial console prevents
> > > dom0 from booting. Serial works until Xen tries to hand off to dom0.
> > > The specific crash varies with the arguments passed to iommu:
> > > iommu=1,debug console=com1 com1=115200,8n1
> > > Xen goes into an infinite loop
> >
> > You don't need iommu=1, PVH Dom0 already requires an iommu and won't
> > boot without it.
> >
> > > iommu=1 console=com1 com1=115200,8n1
> > > Xen either receives an NMI in process_pending_softirqs or gets
> >
> > According to the logs below you are manually injecting an NMI by
> > pressing the 'N' debug key.
> >
> > > stuck in __sync_local_execstate
> > > iommu=1
> > > dom0 boots fine, but USB doesn't work (as others have recently
> > > posted about). I'm using xen staging and linux xen/tip.
> > > Example logs for the first two cases are attached.
> >
> > You also seem to be using UEFI, I have to admit I haven't tried PVH
> > Dom0 on UEFI yet.
> >
> > > (XEN) Latest ChangeSet: Wed Jul 25 15:38:23 2018 +0100 git:f776264532
> > > (XEN) Bootloader: EFI
> > > (XEN) Command line: dom0_mem=1G,max:1G iommu=1 console=com1 
> > > com1=115200,8n1 dom0=pvh x2apic=1 nosmp=1
> >
> > Can you try to boot without the x2apic=1 and nosmp=1 options? Also
> > please set iommu=debug only.
> 
> I'm not pressing any keys. I tried again with iommu=debug and made sure not
> to press anything. Still getting an infinite loop. I attached the log for
> reference.

Oh, Xen is receiving a bunch of key presses for sure. Can you try with
a different serial to USB adapter maybe? And a different null modem
cable?

Have you tried booting without dom0=pvh? It looks like the serial
issues you are seeing are not directly related to the Dom0 mode.

Thanks, Roger.

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