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

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

On Sun, Sep 13, 2020 at 01:12:39PM +0200, Marek Marczykowski-Górecki wrote:
> On Thu, Sep 10, 2020 at 12:58:57PM +0200, Marek Marczykowski-Górecki wrote:
> > On Thu, Sep 10, 2020 at 12:41:04PM +0200, Roger Pau Monné wrote:
> > > Adding toolstack maintainers.
> > > 
> > > On Thu, Sep 10, 2020 at 12:29:21PM +0200, Marek Marczykowski-Górecki 
> > > wrote:
> > > > On Thu, Sep 10, 2020 at 10:51:48AM +0200, Roger Pau Monné wrote:
> > > > > 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.
> > > > 
> > > > Sure, will do.
> > > > It may be also something else: maybe it acpi/apic settings were broken
> > > > before, but did not results in a domU crash this way.
> > > > FWIW when looking into /var/lib/xen/*-libxl-json I clearly see
> > > > difference between b_info.{acpi,apic} and b_info.u.hvm.{acpi,apic}.
> > > 
> > > I think libxl__domain_build_info_setdefault should check whether
> > > b_info.u.hvm.{acpi,apic} is set and copy those into b_info.{acpi,apic}
> > > if those are not set?
> > 
> > Looking at libxl__domain_build_info_setdefault this is not the case.
> > Instead there is libxl__acpi_defbool_val which looks at both.
> > Oh, and there is no similar thing for apic -> b_info.u.hvm.apic is
> > ignored!
> > 
> > > Toolstack people is more likely to have an opinion here, or to help
> > > debug the issue.
> 
> Ok, The crash reported initially was caused by a different thing: using
> seabios.bin instead of seabios-256k.bin (should that really cause the
> crash? shouldn't 128k seabios build work too?). But in any case, I think
> the b_info.u.hvm.{acpi,apic} is also not in a good shape.

Does 128K SeaBIOS have Xen support enabled?

Roger.