Proposal to modify behavior of installworld

[Matthew Dillon]

:I propose that /usr/src/Makefile be changed to optionally backup the 
:important directories of world prior to overwriting the binaries (and 
:set the option default on) so that it's possible to rollback world 
:without having to download the latest snapshot image and cpdup it all. 
:And "make rollbackworld" option (or similar) should be added to the 
:makefile.
:
:I'd even have an option to configuration to keep the last X versions.
:
:What do people think?
:This functionality would be invaluable, especially to those systems not 
:running hammer (although I don't think hammer would be all that useful 
:in the case that dozens or hundreds of binaries are corrupted).
:
:Anyone have an alternative proposal?
:
:John

    There are going to be serious issues with build/install behaviors.  For
    example, I often installkernel several times before actually rebooting,
    and sometimes (though not often) I will installworld several times
    prior to actually rebooting to test it.

    This is precisely why I have a boot-menu option to boot kernel.bak,
    which is manually constructed (cpdup /boot/kernel /boot/kernel.bak)
    and is not touched by the installkernel target (installkernel only
    backs up to kernel.old).

    So I would propose that the world-backup mechanic be a manual target
    and not an automatic process.  e.g. like:

	make backupworld
	make restoreworld

    I do not think it would be a good idea to automatically backup the world
    when doing an installworld because of the issue of potentially doing
    multiple installworlds of unstable source and having your backup get
    blown away.

    However, the buildworld/installworld targets *COULD* warn you when
    there is no backup or the backup is very old (like over a month old)
    and suggest that you make a backup via the backupworld target before
    installing.

					-Matt
					Matthew Dillon 
					<dillon at backplane.com>