Branching for netbsd-10 next week

[Martin Husemann <martin%duskware.de@localhost>]

Hey folks,

after the EA changes are in current now and all tests look good, we can
finally move on and branch for netbsd-10. Proposed date is next wednsday.

We have quite a few things to finish before the final release, but this
gets things moving - and I hope it will not take more than three months
to get the release out of the door.

Before the branch one final issue needs to be decided, and I would like
to solicit your feedback on this:

With the new EA-enabled variant of FFSv2 (see
https://wiki.netbsd.org/features/UFS2ea/ for details) we have the choice
to use ACLs and EAs on FFS file systems - which makes them incompatible
with all prior releases and other operating systems - or to forbid them.

The installer offers upto three options for FFS file systems:

 - FFSv1, typically only used with bootloaders that did not get
   FFSv2 support yet or firmware that loads the kernel directly
   (examples: mac68k or shark).

 - FFSv2, compatible with older releases but not supporting EAs/ACLs.
   In read-only mode partly compatible with other operating systems.

 - FFSv2ea, with full support for EAs and ACLs, but incompatible with
   all prior NetBSD releases and all other operating systems (the
   file system superblock has a different magic number, so will be
   rejected by older code).

Currently the installer defaults to creating FFSv2ea file systems for new
installations, so if you do intend to share a partition with older NetBSD
kernels, be sure to change the filesystem type.

This will require a good description in the release notes, and probably
more extensions to the wiki page pointed to above.

Now the question: should the default install really use this new FFS type,
or should it default to plain FFSv2?

The change is trivial and from my PoV both choices have serious downsides:

 - unaware users may install FFSv2ea file systems and later find the need
   to access them from older NetBSD kernels. "Downgrading" them is
   quite easy using the ufs2ea-flip tool mentioned in the wiki page,
   but it is not "plug & play".

 - if FFSv2ea is not the default, most new installs will create non-EA
   enabled file systems and 
    - the EAs will not get much testing
    - packets from pkgsrc (like samba) will continue to have the corresponding
      options disabled by default
    - users will have a hard time to find the conversion options later.
      It is hidden in fsck_ffs(8) and quite simple: after having made
      sure your bootloader is up to date, boot to single user and
      run something like: "fsck_ffs -c ea /"

So, what should be the default FFS type for new installs in netbsd-10 ?

Martin