Gotchas to Downgrade from 7.0-CURRENTto FreeBSD 6.1-PRERELEASE

[M. Warner Losh]

In message: <20060311213529.epb13ogpggk00ws0 at mail.bafirst.com>
            eculp at bafirst.com writes:
: I've lost track a bit of the differences between current and 
: 6.1-prerelease.  I don't remember anything major that would cause 
: problems.  Does anyone know of a potential gotcha or have suggestions 
: the smooth the pathe or has done this since the freeze?
: 
: The machine that I am going to downgrade is my wife's and I don't 
: really want to recompile roughly 540 ports that are installed but . . . 
: , if need be . . . . ;) Problems with the linuxpluginwrapper port in 
: current started this.  She likes to have her flash and pdf in the 
: browser even though all the other plugins that she uses work.  I think 
: she will probably prefer the stability of RELENG_6 in the long run.

There are two areas where there will be problems.  First is shared
libraries.  Many of them have, iirc, been bumped in -current.  Be
careful here.

Second, there may be kernel issues where while doing the downgrade you
could hose yourself.  Esp in the area of mounting /.

My suggestion is do the following for the downgrade (this order is
different than a normal upgrade, and really isn't supported, so #2
below is extra important):

	(1) Buildworld of RELENG_6
	(2) full dump, or cope w/o.
	(3) installworld of RELENG_6	Yes, before install kernel
	(4) install kernel
	(5) reboot
	(6) find all the shared libraries whose version has gone
	    backwards using ls -l and comparing times.  Delete new
	    versions.  They may interfere with new port building
	(7) Rebuild all ports from scratch.  Maybe consider installing
	    them from packages, or at least the portupgrade series.
	    make sure you force a recompile of all ports via portupgrade.

If, at any point after #2 you are hozed, fall back to #2 and try
again.  Alternatively, do a fresh install after #2 and grab your data
files from step #2.  Build everything you need.

: thanks for your warnings, observations and suggestions,

I've done this half way between 6.0-RELEASE and today with a -current
that was a little too green for the hardware it was on.  I was anal
beyond belief to make sure that nothing from the date of the last
-current install was left on the system after I was done.  The above
is from memory, and your milage may vary.

: PS.  BTW, there isn't a RELENG_6 ports tag, is there?  It is still 
: current, isn't it?

/usr/ports isn't branched, but works on all /usr/src branches in
question here (current and RELENG_6).

Warner