Re: Console output stops on dbgp=xhci

[Tamas K Lengyel <tamas@xxxxxxxxxxxxx>]

On Thu, Sep 15, 2022 at 3:56 AM Jan Beulich <jbeulich@xxxxxxxx> wrote:
>
> On 15.09.2022 02:41, Tamas K Lengyel wrote:
> >>> Do you have any idea what might be going on and preventing the output
> >>> from showing over USB3 afterwards? The /dev/ttyUSB0 device is still
> >>> present on the receiving side, just nothing is being received over it.
> >>
> >> There are few more patches in the series that are de facto required.
> >> Especially those about IOMMU, otherwise it can only possibly work with
> >> iommu=0 (which I'm not sure if even is enough).
> >
> > Unfortunately with iommu=0 Xen doesn't boot at all for me. I see this
> > on the console:
> >
> > (XEN) Panic on CPU 0:
> > (XEN) FATAL PAGE FAULT
> > (XEN) [error_code=0011]
> > (XEN) Faulting linear address: 00000000328b3a54
>
> Perhaps in another thread, could you post details about this? I guess
> we want to address this independent of your XHCI issue. That's an
> attempt to execute code outside of the Xen image - the only reason I
> can think of for this would be an EFI boot services or runtime
> services call, with (possibly but not necessarily) quirky EFI firmware.
> Any other context this is appearing in would quite certainly require a
> fix in Xen, and I don't see how "iommu=0" could affect the set of EFI
> calls we make.

This was indeed observed with a xen.efi booted directly from UEFI.
Beside the limited boot log I get through xhci I don't have more
insight but happy to send that (and anything else you think would be
useful).

Tamas