From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kiszka Subject: Re: Q: status of kvm/ subdir in qemu-kvm tarball? Date: Sun, 27 Feb 2011 19:36:31 +0100 Message-ID: <4D6A99AF.8070800@web.de> References: <4D64E9C6.8000505@msgid.tls.msk.ru> <4D64F008.7050308@siemens.com> <4D64F2C0.4000609@msgid.tls.msk.ru> <4D650479.30609@siemens.com> <4D650884.3090801@msgid.tls.msk.ru> <4D650F85.10502@siemens.com> <4D651A1D.8030206@msgid.tls.msk.ru> <4D652040.9000309@siemens.com> <4D6A7BC1.9020703@redhat.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enig84360DC928A4BF9F0CA56FE2" Cc: Michael Tokarev , KVM list To: Avi Kivity Return-path: Received: from fmmailgate01.web.de ([217.72.192.221]:48445 "EHLO fmmailgate01.web.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750822Ab1B0Sgh (ORCPT ); Sun, 27 Feb 2011 13:36:37 -0500 In-Reply-To: <4D6A7BC1.9020703@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig84360DC928A4BF9F0CA56FE2 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable On 2011-02-27 17:28, Avi Kivity wrote: > On 02/23/2011 04:57 PM, Jan Kiszka wrote: >> > >> > The only situation where using kernel headers not provided >> > by qemu itself is when you want to build qemu for older >> > kernel and omit some features and runtime tests. But this >> > is hardly a good goal to support. >> >> I don't think the goal of the #ifdefs was ever some kind of size >> optimization but just for the sake of avoiding build breakages. >> >=20 > Yes. >=20 >> Well, "rm -r kvm" is a rather minor thing. But the header discussion i= s >> important IMO as we continue to see breakages in KVM builds (mostly qe= mu >> upstream) due to missing #ifdefs. That means: >> - we do not test all variants (because it's impractical) >=20 > We could teach buildbot about it. We could, but the test matrix wouldn't be simple. Think of CAPs that depend on other CAPs. I don't think it would be worth the effort. And if we forget to update a test after adding a CAP, the situation won't be different from today. >=20 >> - people use older headers >> - too much effort is wasted on fixing distributed problems that can = be >> solved centrally >=20 > Yes. But on the other hand carrying headers is the Wrong Thing, isn't > it? Well, there are also different views on this, see e.g. http://kernelnewbies.org/KernelHeaders > If everyone did that we'd be in a mess of duplication. I'd like > not to contribute to that. Not all distros keep their kernel headers sufficiently recent and/or users forget to update them when updating the kernel (I just noticed that vhost remained off in some builds here due to pre-historic distro headers). As long as we continue adding or changing the kernel ABI, qemu will face these problems. We can't avoid a certain degree of mess, either in form of in-tree header copies or via a continuously increasing number of #ifdefs in our code. I'm really convinced now the former is both more user-friendly and cleaner than the latter. Jan --------------enig84360DC928A4BF9F0CA56FE2 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.15 (GNU/Linux) Comment: Using GnuPG with SUSE - http://enigmail.mozdev.org/ iEYEARECAAYFAk1qmbIACgkQitSsb3rl5xSwkwCgnPVElf0ciCl6fLkp97zCf7Na gGAAoJ5NQkH4DZk1K3raRsbkDl56UGZr =9ID7 -----END PGP SIGNATURE----- --------------enig84360DC928A4BF9F0CA56FE2--