Date: Mon, 22 Aug 2016 11:21:45 +0300 From: Andriy Gapon <avg@FreeBSD.org> To: Allan Jude <allanjude@FreeBSD.org>, src-committers@FreeBSD.org, svn-src-all@FreeBSD.org, svn-src-head@FreeBSD.org, Toomas Soome <tsoome@FreeBSD.org> Subject: Re: svn commit: r303630 - in head/sys: boot/zfs cddl/boot/zfs Message-ID: <893dc513-69b4-ae9e-e3d3-2d2d02d04348@FreeBSD.org> In-Reply-To: <201608011937.u71JbhGD055117@repo.freebsd.org> References: <201608011937.u71JbhGD055117@repo.freebsd.org>
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On 01/08/2016 22:37, Allan Jude wrote: > Author: allanjude > Date: Mon Aug 1 19:37:43 2016 > New Revision: 303630 > URL: https://svnweb.freebsd.org/changeset/base/303630 > > Log: > Make boot code and loader check for unsupported ZFS feature flags > > OpenZFS uses feature flags instead of a zpool version number to track > features since the split from Oracle. In addition to avoiding confusion > on ZFS vs OpenZFS version numbers, this also allows features to be added > to different operating systems that use OpenZFS in different order. > > The previous zfs boot code (gptzfsboot) and loader (zfsloader) blindly > tries to read the pool, and if failed provided only a vague error message. > > With this change, both the boot code and loader check the MOS features > list in the ZFS label and compare it against the list of features that > the loader supports. If any unsupported feature is active, the pool is > not considered as a candidate for booting, and a helpful diagnostic > message is printed to the screen. Features that are merely enabled via > zpool upgrade, but not in use, do not block booting from the pool. > > Submitted by: Toomas Soome <tsoome@me.com> > Reviewed by: delphij, mav > Relnotes: yes > Differential Revision: https://reviews.freebsd.org/D6857 It is really great to get a helpful diagnostic message when an unsupported feature is seen. Thank you for that! But I would prefer that the check is done on a filesystem level, not on a pool level. That is, I would like to be able to enable features that are not supported by ZFS boot chain on a boot pool as long as I do not enable such features on a boot filesystem. E.g., the large blocks support could be one of such features. And, as I've said in another email, I really do not think that we should strive to support all possible (non-essential) ZFS features in the ZFS boot chain. -- Andriy Gapon
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