Re: libxl - b_info.{acpi,apic} behaves differently than b_info.u.hvm.{acpi,apic}

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

On Thu, Sep 10, 2020 at 05:57:23AM +0200, Marek Marczykowski-Górecki wrote:
> Hi,
> 
> After updating from Xen 4.13 to Xen 4.14 I have troubles starting any
> HVM: just after hvmloader saying "Invoking SeaBIOS" I get "(XEN) MMIO
> emulation failed (1): d29v0 32bit @ 0008:fffeedf d -> "
> 
> I come to a situation where seemingly the same domU started via xl
> works, while when started via libvirt it crashes. This seems to be
> related to xl setting b_info.{acpi,apic}, while libvirt setting
> b_info.u.hvm.{acpi,apic}. Modifying libvirt to use the former fixes the
> issue.

Could you print the values of the involved fields at the end of
libxl__domain_build_info_setdefault in both cases?

I'm not able to spot what changed between 4.13 and 4.14 that could
alter the behavior, but knowing the values at that point might make
it easier.

> So, handling the old option got broken sometime between 4.13 and 4.14.
> Or perhaps it is some other related side effect.

Libvirt master tests seem to have been failing for some time (60 days)
in the build phase [0], maybe you are using a newer version of libvirt
than what osstest is currently testing? (Xen flights are currently
stuck at libvirt commit 2c846fa6bcc11929c9fb857a22430fb9945654ad).

Thanks, Roger.

[0] 
http://logs.test-lab.xenproject.org/osstest/logs/152881/build-amd64-libvirt/6.ts-libvirt-build.log