Note: when CHECK is set, targets.log only.
targets.log will be moved to $(BUILDDIR)/reports/

This should save a few repetitive lines during multi image build,
albeit the ideal result should only print out the BRANCH once
as it's invariant for the whole build process (no, you can't
just go ahead and echo it where it gets checked/defined
since that's not the recipe body).
Suggested by mike@

We cannot get IMAGE_OUTPATH from the build.log, and there is currently
no other mechanism. Creating a CHECK directory was a bad idea. It should
have been created only for CHECK, but it was always created when DEBUG
was not enabled. So it's better to just issue a warning.

Ports have suffix _$(arch) appended to the branch name.

So much clearer and easier.
Thanks glebfm@ for the idea.

check conditions of  make  for equality of variables with an empty value
instead of check definition.
A defined but empty variable under all these conditions results errors.

See-also: https://bugzilla.altlinux.org/show_bug.cgi?id=40148

Also now there will be no garbage (temporary directories) when
executing DIRECT_TARGETS.

You must use the GNU MAKE variable, not a shell variable, and must
pass the REPORT variable to reports.mk.

make distclean should be launched after copying the log when
debugging is enabled.

Before this change, we could have 0 exit code from the main
make process even when some targets failed to build on some
architectures:

$ make ARCH=mipsel [...] vm/tavolga-regular-mate-ex.recovery.tar
** ARCH: mipsel
10:15:06 cleaning up
10:15:06 initializing BUILDDIR: build/
10:15:06 preparing distro config: build/distcfg.mk
make[1]: *** No rule to make target 'use/systemd-coredump', needed by 'profile/.extra'.  Stop.
[nightly-mipsel@loongson5 mkimage-profiles]$ echo $?
0

Use `make -k' to get the old behaviour.

This one reduces the amount of output that's only
interesting when one is actually watching the console
during builds (at least the early stage) -- these tend
to look boilerplate and be useless when inspecting the
output of a large batch build like [[regular]] one.

This one is long overdue as I keep forgetting to update
the published copy of generated documentation all the time.

Note that you must pass DOCS_PUBLISH (as a local directory
or host:dir suitable for rsync/ssh) via make arguments,
environment or ~/.mkimage/profiles.mk file.

This inobvious buglet has been spotted shortly after
1.1.0 refactoring was roughly over; the problem is
that armh-specific targets would get ignored without
explicit ARCH=armh.

It's commit 768df7e9
which streamlined introspection within main.mk
and a bug in Makefile which left ARCH empty
even upon having autodetected it for ARCHES.

The current version is more straightforward as a bonus.

...and on other direct non-build actions like clean or help.
How could this stay overlooked for so long?

Somewhat kludgy unfortunately and might need even more tweaking,
I have only armv7l board handy at the moment to verify that
the transformation is going to work.

QEMU is bailing out here and now ("Exec format error").

Example sources.list.sisyphus.armh of the season:

  rpm http://ftp.altlinux.ru/pub/people/asdus/sisyphus armh classic
  rpm http://ftp.altlinux.ru/pub/people/asdus/sisyphus noarch classic

Docs should live happily together, after all,
and toplevel should be more or less uncluttered :)

Adjusted/rewrote as appropriate as well.

`help' used to be the default target described at the very top
of the toplevel makefile but that got broken with g2f307fff;
spotted while discussing m-p with enp@.

say() redirects to stderr already.

As it happens, adding another architecture required almost no changes;
native 32-bit ppc build took only ARCH and a repo, qemu-ppc one still
has problems (/.host/entry hangs while unpacking setup for fakedata).

Proof of concept on a QS22:

  $ make ve/bare.tar.gz
  ** ARCH: ppc
  /bin/sh: rpmvercmp: command not found
  21:41:01 cleaning up
  21:41:03 initializing BUILDDIR: build/
  21:41:03 preparing distro config
  21:41:05 starting image build (coffee time)
  21:42:48 done (1:42)
  ** image: $TMP/out/bare-20120716-ppc.tar.gz [21M]

The only thing to be fixed was setarch(8) symlinks assumption
that is correct for x86 but not for ARM.

There's also some hasher(7) setup to be done:

  mkdir -p ~/.hasher
  echo >> ~/.hasher/config <<-EOF
  def_target=arm
  #cache_dir=$HOME/tmp	# depends on RAM/storage configuration
  EOF

...and of course apt(8) should be properly set up too.

An example PoC build on a CM-A510 board (tmpfs):

  $ make BRANDING=altlinux-centaurus ve/bare.tar.gz
  ** ARCH: arm
  18:10:45 initializing BUILDDIR: build/
  18:10:45 preparing distro config: build/distcfg.mk
  18:10:46 starting image build: tail -f build/build.log
  18:14:49 done (4:02)
  ** image: $TMP/out/bare-20120706-arm.tar.gz [23M]

~/.mkimage/profiles.mk is useful but not requisite by any margin;
no need to make noise trying to make it either.

Raw disk images are convenient and universal
but there are custom formats like Qemu's qcow2
providing additional features, e.g. copy-on-write
or space savings.  All of this ultimately belongs
to mkimage but in the mean time has been implemented
here as well.

It appears that while splitting off main.mk we've lost
the ability to pass e.g. ARCHES via custom configuration;
thanks dkr@ for spotting this.

It's hard to tell a successful build from a failed one
if downstream hides the exit code; it's useless to continue
a `for' loop if a pipe shoves that to a subshell; well it seems
that a bashism is worth a thousand quirks with extra fds here.
Minor regexp enhancements are also due.

reports.mk made a bit more resilient/prudent either.

Thanks glebfm@ yet again :)

Trying to extract reports for a failed build is a bad idea.

bin/ prefix tried to become a permatemp(tm).  No way.

The purpose is being able to examine particular target interdependency
graph for a given image having been configured to avoid convoluted
dependencies (loops in particular).

The implementation is based on SHELL hook hint by John Graham-Cumming:
http://cmcrossroads.com/ask-mr-make/6535-tracing-rule-execution-in-gnu-make

There was a somewhat subtle Makefile->main.mk rename leftover
lurking in "everything" target: the default Makefile got used,
not the supposed main.mk -- which resulted in an attempt to
get way too much job done (the number of builds per target
became $ARCH squared, not just $ARCH).

Huge thanks to led@ for being an inspiring pedantic!

The point is to give Colin S. Miller the credit for
a hack to get the current goal's word-in-a-list position:
http://lists.gnu.org/archive/html/help-gnu-utils/2010-05/msg00004.html

The former toplevel Makefile is now toplevel main.mk;
this change allows for multi-target, multi-arch processing
in the current toplevel Makefile.

As the "build" symlink semantics change quite considerably
when one is doing bulk builds (several pruned builddirs might
be useful for comparison), BUILDDIR is now much more likely
to be recreated: the cases when it will persist are when it's
either a single-image build or when the prefix hasn't changed.

There are some more or less subtle bugfixes and enhancements
all over the map as well.

Done within 20111230..20120102 timeframe, actually...

distro/live-builder target used to employ a few duplicated
packages that might make it to a list but as the list would
have only a single user so far these were moved to a target-
specific variable (hm, weird but "private" modifier broke).

Actually this is the proper rewrite that was looming ever since
tgz support was introduced: there are multiple archive formats
supported by mkimage, and there are multiple compression methods
available as well.

So the bullet got bitten yet again along with the "goal parser"
which should be more straightforward by now.

Thanks dkr@ and mithraen@ for the inspiration of this evening.

Partially reverts "Makefile: presume a distro by default" commit:
plain `make' should better help the user to decide the target
rather than rush to build them all upon her.

When ve/ support was introduced, a simple "make icewm.iso"
had to turn into the more elaborate "make distro/icewm.iso".
This latter one involves several keystrokes more, which is
not even (environ)mentally friendly.

This was supposed to get fixed somewhere down the road with
a fallback but the elegance of IMAGE_* setup waterfall barred
me from tweaking IMAGE_TARGET at once (and the downstream fixup
would imply re-tweaking the consequent variables as well which
is blatantly anti-mkimage-profilic being a brute fork).

OTOH testing for a "directory" part of the goal is going to
either deadlock on IMAGE_CLASS or duplicate its assignment.

So now when I've had enough typing an extra "distro/",
I'm going to just bite the bullet and tweak IMAGE_TARGET
with a test duplicating IMAGE_CLASS assignment indeed
(testing for e.g. "/" results in a different test,
which would be worse yet).

Please suggest a more elegant solution if you invent one!

Preferences might be somewhat interesting too: while the official
ones shouldn't influence the build result at all, there's no whitelist
so all kinds of weirdness can be stuffed into local config in principle.
That should be diagnosable at least.