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Re: [Xen-devel] HVM domains crash after upgrade from XEN 4.5.1 to 4.5.2

Am 17.11.15 um 00:01 schrieb Andrew Cooper:
On 16/11/2015 19:16, Atom2 wrote:

Am 16.11.15 um 16:31 schrieb Konrad Rzeszutek Wilk:
Your analysis was absolutely spot on. After re-thinking this for a
moment, I thought going down that route first would make a lot of
as PV guests still do work and one of the differences to HVM domUs is
that the former do _not_ require SeaBIOS. Looking at my log files of
installed packages confirmed an upgrade from SeaBIOS 1.7.5 to
1.8.2 in
the relevant timeframe which obviously had not made it to the
of xen-4.5.1 as I did not re-compile xen after the upgrade of

So I re-compiled xen-4.5.1 (obviously now using the installed SeaBIOS
1.8.2) and the same error as with xen-4.5.2 popped up - and that
to strongly indicate that there indeed might be an issue with
SeaBIOS as
this probably was the only variable that had changed from the
install of xen-4.5.1.
I recall seeing this way back in Fedora 20 days. I narrowed it down the
SeaBIOS version that was a standalone package to not have CONFIG_XEN.

Having that fixed in the SeaBIOS package fixed it.
Hi Konrad, Doug, Andrew (specifically added to this part of the thread)!
Konrad, you might have found an interesting point. I did have a look
at the ebuild for the failing version and in there I found the
following comment:
====== comment from ebuild =======
     # Upstream hasn't released a new binary.  We snipe ours from
Fedora for now.
     # http://code.coreboot.org/p/seabios/downloads/get/bios.bin-${PV}.gz
====== end comment from ebuild =======
which might in fact underline that there might be an issue similar to
what you described above.

What is also pretty interesting is the fact that the old (working)
SeaBIOS version 1.7.5 installed as "bios.bin" under /usr/share/seabios
is actually 262.144 bytes in size whereas the new (invalid) SeaBIOS
1.8.2 installed in the same location is only half as big: 131.072 bytes.

I checked at the download site and the 1.8.2 binary version is indeed
not available from http://code.coreboot.org/p/seabios/downloads/. But
both the binary versions for 1.7.5 and 1.8.0 are available and both
are acutually 262.144 bytes in size, so I'd be very surprised if the
1.8.2 version is really only half that size. By the way, the old
working version (according to the ebuild) was directly downloaded from
the above url and also shows an identical SHA1 digest to that version
available for download there.

To me this looks as if something is really wrong here. If anybody of
you has access to a 1.8.2 version, could you please confirm whether
there's really that big a size difference between the 1.7.5 and the
1.8.2 versions? Or is that difference probably attributable to the
missing CONFIG_XEN option?

Andrew: I havent't gotten around to run the debug version of the
hypervisor again, but if the current suspicion turns out to be true,
there's probably not much value in that anyways. Would you agree?
Sadly not.
Fair enough. I'll try to get things done, hopefully somewhen tomorrow or, in case that doesn't work out, on Wednesday and will send you the requested information.

Many thanks for your support, Atom2
I accept that this issue is possibly fixed in newer SeaBIOS by working
around the issue.

However, I stand by my original point.  *There is no way the guest
should be able to get into this situation in the first place*, and its
implication of *there is a genuine hypervisor bug which we should track
down*, irrespective of whether the issue has been worked around elsehow

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