[arch-general] archroot - proper way to Start Over? (rm -r $CHROOT/$USER)?

[David C. Rankin]

On 03/02/2012 04:48 PM, C Anthony Risinger wrote:
> IIRC makechrootpkg used to create an overlay/union before starting,
> which would keep your original root intact.  if you put your builds on
> a btrfs filesystem i believe makechrootpkg will snapshot the fs before
> starting (i know im mixing mkarchroot and makechrootpkg a bit here
> ...)
> 
> imo, the most effective way is to use an overlay.  this FUSE based one
> work just fine:
> 
> http://podgorny.cz/unionfs-fuse/releases/
> 
> ... as do many other methods (DM, btrfs, overlayfs, unionfs, etc etc),
> though i persoanlly like the FUSE impl because it can cope with stuff
> better without less risk of crashing.  you can then use --bind mounts
> or multiple overlays to do interesting things too.
> 
> make sure you've enabled `ccache` in your /etc/makepkg.conf, and
> adjusted your `-jN` makeflag to an appropriate number.  i keep a 10GiB
> cache around; i can blow away the webkit tree and start completely
> fresh, apply my in-progress patchsets, and have a working package in
> ~2 minutes (normally a 3+hr build).

Thanks C Anthony,

  It's the alphabet soup on top of the union filesystem and separate rw layer
concepts that has my eyes rolling back in my head at the moment :)

(re-reading the paragraphs for a 2nd time hoping it will all sink in)

  OK, so what your are saying is that after I make friends with the snapshot
concept (whether DM, btrfs, overlayfs, etc...) I can basically keep snapshots of
different build 'points' in cache and switch back and forth relatively easily
once I learn how -- right? So if I have one set of Trinity packages based on Qt3
and another set based on TQt3, I can pickup building at the last good point of
progress in either set by configuring the snapshot I need to create that
environment? Like if I have built the dependencies through the snapshots below:

     Trinity/Qt3                    Trinity/TQt3
       Arts                           Arts
       Dbus                           Dbus
       caldav                         caldav
       ...                            ...
       tdelibs  (cache snapshot A)    tdelibs
                                      tdebase  (cache snapshot B)


  I could then configure the chroot to switch back to 'cache snapshot A' and
continue building on Trinity/Qt3 at that point after I had saved snapshot B and
reverted to the A cache?

  Would you happen to have a favorite link to a page that might help me get a
bit smarter on this? :)


-- 
David C. Rankin, J.D.,P.E.