Date: Thu, 3 Apr 2014 09:35:46 -0400 From: Glen Barber <gjb@FreeBSD.org> To: Frank Leonhardt <frank2@fjl.co.uk> Cc: freebsd-doc@freebsd.org Subject: Re: Downplaying a serious issue Message-ID: <20140403133546.GC14379@glenbarber.us> In-Reply-To: <533D5D3F.5020409@fjl.co.uk> References: <861txffcgh.fsf@shell.gmplib.org> <alpine.BSF.2.00.1404022118570.76387@wonkity.com> <20140403035800.GR14379@glenbarber.us> <86k3b697nt.fsf@shell.gmplib.org> <20140403113605.GZ14379@glenbarber.us> <533D5D3F.5020409@fjl.co.uk>
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--6dGMKdYe2Ft9UtxE Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Apr 03, 2014 at 02:08:15PM +0100, Frank Leonhardt wrote: > On 03/04/2014 12:36, Glen Barber wrote: > >On Thu, Apr 03, 2014 at 09:47:02AM +0200, Torbjorn Granlund wrote: > >>Glen Barber <gjb@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 n= ow > >>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/i3= 86 > >>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: >=20 > ------------------------------------------ >=20 > "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. >=20 > It causes various errors and makes FreeBSD quite unstable. Although the > cause is still unclear, disabling unmapped I/O works as a workaround." > etcetera >=20 > ------------------------------------- >=20 > 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). >=20 > 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. >=20 > Does the problem exist on previous releases? >=20 No. > 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. >=20 > Incidentally, I don't see this as a bug in FreeBSD. A hypervisor is suppo= sed > to transparent to the OS, emulating the hardware that the OS thinks it ha= s, > to perfection. This is a broken VM, as clearly it's not behaving as the r= eal > hardware would. Or is it? >=20 The cause is unclear. Glen --6dGMKdYe2Ft9UtxE Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.22 (FreeBSD) iQIcBAEBCAAGBQJTPWOyAAoJELls3eqvi17Q3lgP/RDgE3P8lQG/aVc9ClKoPodZ 1Rgyx0XRiTaU10uygMdQJJZlEAH6dIhGbdSTzpeICfSdLcYbfpwLmkvvFRjaXQhr Cqpj9EiZu4KEYznjgwXkW+jpjt5g6Iwe2XBO8cQ0vUVmgGux4lOnLmJ6lh//u904 6ZgWdUInWh689IAcPYon0lIA23+DvkqzG7+stKwRVdqwuiON58odVl5BMEgQw+H1 ZqTTmCM0v4wSI25UAPDisSPLN+v3IIpwEikvPetT9FpvsmdSgqIz5ACsduu++v+h HMFshrreRj+w8JV3I3bH4JyHqpP3Ln6eyjefqt6RSzftPx0KQ87wIJq86oeMQT7e TLtbBEqpCeL6cm8+G81qyAPtaDtii2NtFO4UQb/xF2c6io+lOMhdRexlgPRdVq1f R+TFx0KeV0c9UWxJGtQwr2owojLeHgpg45Cb7yjQMBoeuhiF4k+akha/II1ENe7N 28NnxOr3uiLCSImDEaPgnRp3UHHkU+Uokbte2vbgYLlcHEQRna8lDpZjA4cevR0p EPyoUDPNlrBo5omgY2mTfcK3uEDLoL0asnB5/Jxkf+QoQzC4wt9Yehm7EedivlgP fjUaU7mvM4dks3rWsCu/zSB16IACQ1LkaXTcKZpCIpmdK04fv6wdJ+iERZy8WxRE j2pLVidA6pD9pvdcsw9G =CTlo -----END PGP SIGNATURE----- --6dGMKdYe2Ft9UtxE--
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