Date: Thu, 03 Apr 2014 11:31:57 -0400 From: Allan Jude <freebsd@allanjude.com> To: freebsd-doc@freebsd.org Subject: Re: Downplaying a serious issue Message-ID: <533D7EED.1030908@allanjude.com> 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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This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --l3FSjnMQSFo3RTSPucrtdBh8qk7XEtkRT Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable On 2014-04-03 09:08, 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= >>> now >>> the major downplay at http://www.freebsd.org/releases/10.0R/errata.ht= ml, >>> where this is a minor hardware specific problem. >>> >>> I have not found one piece of PC hardware where it does not happen un= der >>> virtualisation. Please let me know some configuration where >>> FreeBSD/i386 >>> works under a type 1 virtualiser? Perhaps Bhyve is FreeBSD-compatibl= e? >>> >> Does not happen on my VirtualBox host. >> >> Glen >> > I've been following this discussion with some alarm, but have now looke= d > 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). Not very much detail has been provided about what exactly 'is not working' in these other hypervisors. I would hesitate to write that FreeBSD 10 doesn't work in Xen from a single user report, when Colin Percival has FreeBSD 10 images for 32bit Amazon EC2 (Xen) that I've heard no reports of problems with http://www.daemonology.net/freebsd-on-ec2/ >=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? The 'unmapped IO' feature was added in FreeBSD 10, so the feature that is related to (if not causing) the problem is new. >=20 > 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 > 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? >=20 > Regards, Frank. >=20 > _______________________________________________ > freebsd-doc@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-doc > To unsubscribe, send any mail to "freebsd-doc-unsubscribe@freebsd.org" --=20 Allan Jude --l3FSjnMQSFo3RTSPucrtdBh8qk7XEtkRT Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.16 (MingW32) Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQIcBAEBAgAGBQJTPX7tAAoJEJrBFpNRJZKfuZcQAJApRQsa0a+UezpKVbqTmv4V 6wTPKeHcYEPC2EmFLtglF/+Fd6xhV4m5h3EVjRPZ0OIzONQJqg02kq15CFzP2G00 iLMn0oJum7KgzWCu+sKMvuofqZCPG6zKRUPDLsF8WykAEazYPaiP/P+Pe43G59Af 0mD2hn0PaV1xUlA58++2QmbA2S3zCKQAzL05BVWnTkbJNwSXnrpEqFFF4hEHsbrB VjiUBRQrLCkBv/eSBqJqIf5Rrwr6iOjUddFh9uk6wdJD5DfoOXfsNvK9UdmZKTT9 vg1z+IkeLcpXqEol6ToObDX5Zb0Qh8wdkwVxjYw2hUFxWmx2E6hy8LNa3zfkzRIi la+z8VnL0bUOh2VZO+A8fU3KRNy8odP9Ac4Kq46Ne5WbTO4TmLcERLpdNVO02MIE F5bz3T7zMPdbKhnCW1+ErlpuwvwPLBfpZnuQaBh5iXnH0lndHBMnzp+gyjkKTZB1 lzCvMT51h9LK2rV5X9sIcBMuamF4cUnf3YbBIxC2N0Iv9W34J5Chxgk8u63MZPHk 3eVwV0B0rf8qbRUu5VRHULhgj9hJWg1FsIY4v7xXgh4oBuh7J3NzovxfEcskWoJq 7WTmj1r+e6CLeEeyxlj+ySoprLl2IXx05+g/L7aGW7AyeuNiM+/PWaLOLQjuLCYA 68k/eGzeKyUgnylA/j1E =aJRN -----END PGP SIGNATURE----- --l3FSjnMQSFo3RTSPucrtdBh8qk7XEtkRT--
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