[review request] zfsboot/zfsloader: support accessing filesystems within a pool

[Andriy Gapon]

on 14/04/2012 18:37 Andriy Gapon said the following:
> 
> I would like to ask for a review and/or testing of the following three patches:
> http://people.freebsd.org/~avg/zfsboot.patches.diff
> 
> These patches add support for booting from an arbitrary filesystem of any
> detected ZFS pool.  A filesystem could be selected in zfsboot and thus will
> affectfrom where zfsloader would be loaded.  zfsboot passes information about
> the boot pool and filesystem to zfsloader, which uses those for loaddev and
> default value of currdev.  A different pool+filesystem could be selected in
> zfsloader for booting kernel.  Also if vfs.root.mountfrom is not explicitly set
> and is not derived from fstab, then it gets set to the selected boot filesystem.

A note for prospective testers: the patched loader expect to be started by the
patched zfs boot as it passes an additional parameter for a filesystem guid.
I should probably add some way to distinguish between the older and newer zfs
boot blocks.  Maybe an extra bit in bootflags?  What do you think?

> This should could be used as a foundation for the support of Solaris-like boot
> environment selection.  I believe that other people have already developed
> scripts utilizing ZFS capabilities to provide other aspects of management of
> boot environments.
> 
> I am particularly interested in reviews of my attempt to make ZFS boot support
> arch-independent.  The arches, of course, would have to add some code to make
> use of that support.  Currently I only enabled it for x86.
> 
> Thank you very much!


-- 
Andriy Gapon