On 03/04/2014 12:36, Glen Barber wrote:
On Thu, Apr 03, 2014 at 09:47:02AM +0200, Torbjorn Granlund wrote:
Glen Barber <g...@freebsd.org> writes:
It is not a doc problem.
The issue is specific to certain hardware configurations, and unless
anyone has made any breakthroughs that I am unaware of, the cause is
still unknown.
It happens on:
AMD piledriver running Linux+KVM
AMD piledriver running Linux+Xen
Intel Nehalem running NetBSD+Xen
Intel Sandybridge running NetBSD+Xen
Intel Haswell running NetBSD+Xen
AMD K10 Barcelona running NetBSD+Xen
AMD Bulldozer running NetBSD+Xen
We need more specifics.
I've seen the laughable claim that this is a "bug in Virtualbox", and now
the major downplay at http://www.freebsd.org/releases/10.0R/errata.html,
where this is a minor hardware specific problem.
I have not found one piece of PC hardware where it does not happen under
virtualisation. Please let me know some configuration where FreeBSD/i386
works under a type 1 virtualiser? Perhaps Bhyve is FreeBSD-compatible?
Does not happen on my VirtualBox host.
Glen
I've been following this discussion with some alarm, but have now looked
at the Errata:
------------------------------------------
"FreeBSD/i386 10.0-RELEASE running as a guest operating system
onVirtualBoxcan have a problem with disk I/O access. It depends on some
specific hardware configuration and does not depend on a specific
version ofVirtualBoxor host operating system.
It causes various errors and makes FreeBSD quite unstable. Although the
cause is still unclear, disabling unmapped I/O works as a workaround."
etcetera
-------------------------------------
I don't read this as "down-playing" - it's up front about saying that
there's a problem with every version of VirtualBox. It would, of course,
be useful to add that it doesn't work with other named emulators too
(for a virtual machine IS emulating the I/O hardware).
My concern was that this bug may be present on the real hardware too. I
suspect more people would be running an i386 version as a VM than on
real metal these days.
Does the problem exist on previous releases?
It seems to me that, after research, the list of confirmed incompatible
configurations need to be expanded, especially to encompass other
known-to-fail emulations. A list of "confirmed" problem environments
would make readers wary about untested emulators too.
Incidentally, I don't see this as a bug in FreeBSD. A hypervisor is
supposed to transparent to the OS, emulating the hardware that the OS
thinks it has, to perfection. This is a broken VM, as clearly it's not
behaving as the real hardware would. Or is it?
Regards, Frank.
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