[Qemu-devel] [PATCH 00/24] per-directory Makefile snippets, limit vpath abuse

[Paolo Bonzini <pbonzini@redhat.com>]

One source of complexity in the QEMU source is that we have a very
shallow tree for a source code of over 750,000 lines of code.  In
fact, one third of these lines alone is in one directory, hw/.

As a prerequisite to cleaning up the structure, but as a worthwhile
step on its own, this patchset cleans up the build system so that
separate directories have their own Makefile snippet.  As in the Linux
kernel build system, the overall build system is generally flat (in
the case of QEMU, with one recursive invocation per emulation target).
Subdirectories do not include complete Makefiles, instead they only host
the declarations for a few variables (common-obj-y, universal-obj-y,
obj-y, etc.).  Definitions for all the directories are merged with a
little GNU Make magic (not much, only 20 lines).

Two nice side effects are:

- we can match the source tree and the object tree (for example the
  per-target device models will be in XYZ-softmmu/hw, not in
  XYZ-softmmu; those that are compiled once will be in hw/ rather
  than in the root).

- because the resolution of nested makefiles tracks the nested
  directory, there is no need to use VPATH to find sources in
  the hw/ and target-*/ directory.

- there is a lot less Makefile programming (conditionals, addprefix,
  etc.), replaced by only 20 lines in rules.mak and 1 in Makefile.objs.

The series is entirely bisectable, and mostly consists of boring patches.
If the concept is accepted, I would like to get it in as soon as possible.
I have a few other cleanups on top (I stopped once I undid the diffstat
of this series :)), but they can be covered later.

Thoughts, approvals, rejections?

Paolo


Paolo Bonzini (24):
  remove trace-nested-y
  do not sprinkle around GENERATED_HEADERS dependencies
  add rules for nesting
  move *-user/ objects to nested Makefile
  move obj-TARGET-y variables to nested Makefile
  move libobj-y variable to nested Makefile
  move other target-*/ objects to nested Makefiles
  move rules for nesting to Makefile.objs
  use nested Makefile rules for qom/ objects
  move block/ objects to nested Makefile
  move net/ objects to nested Makefile
  move fsdev/ objects to nested Makefile
  move ui/ objects to nested Makefile
  move audio/ objects to nested Makefile
  move slirp/ objects to nested Makefile
  move qapi/ objects to nested Makefile
  move qga/ objects to nested Makefile
  move target-independent hw/ objects to nested Makefiles
  convert libhw to nested Makefiles
  move per-target hw/ objects to nested Makefiles
  move device tree to per-target Makefile
  libcacard Makefile cleanups
  limit usage of vpath
  compile oslib-obj-y once

 Makefile                                     |   30 ++-
 Makefile.hw                                  |    7 +-
 Makefile.objs                                |  316 ++++---------------------
 Makefile.target                              |  325 ++++----------------------
 audio/Makefile                               |   15 ++
 block/Makefile                               |   11 +
 bsd-user/Makefile                            |    3 +
 configure                                    |   70 +++---
 fsdev/Makefile                               |    6 +
 hw/9pfs/Makefile                             |    9 +
 hw/Makefile                                  |  162 +++++++++++++
 hw/alpha/Makefile                            |    4 +
 hw/arm/Makefile                              |   40 ++++
 hw/cris/Makefile                             |   13 ++
 hw/i386/Makefile                             |   13 ++
 hw/ide/Makefile                              |   10 +
 hw/lm32/Makefile                             |   23 ++
 hw/m68k/Makefile                             |    4 +
 hw/microblaze/Makefile                       |   14 ++
 hw/mips/Makefile                             |    6 +
 hw/ppc/Makefile                              |   32 +++
 hw/s390x/Makefile                            |    3 +
 hw/sh4/Makefile                              |    5 +
 hw/sparc/Makefile                            |    8 +
 hw/sparc64/Makefile                          |    4 +
 hw/usb/Makefile                              |   13 ++
 hw/xtensa/Makefile                           |    5 +
 libcacard/Makefile                           |   17 +-
 linux-user/Makefile                          |    7 +
 linux-user/arm/nwfpe/Makefile                |    3 +
 net/Makefile                                 |   13 ++
 qapi/Makefile                                |    3 +
 qga/Makefile                                 |    4 +
 qom/Makefile                                 |    6 +-
 rules.mak                                    |   21 ++
 slirp/Makefile                               |    4 +
 target-alpha/Makefile                        |    3 +
 target-arm/Makefile                          |    4 +
 arm-semi.c => target-arm/arm-semi.c          |    0
 target-cris/Makefile                         |    2 +
 target-i386/Makefile                         |    6 +
 ioport-user.c => target-i386/ioport-user.c   |    0
 target-lm32/Makefile                         |    2 +
 target-m68k/Makefile                         |    3 +
 m68k-semi.c => target-m68k/m68k-semi.c       |    0
 target-microblaze/Makefile                   |    2 +
 target-mips/Makefile                         |    2 +
 target-ppc/Makefile                          |    3 +
 target-s390x/Makefile                        |    3 +
 target-sh4/Makefile                          |    2 +
 target-sparc/Makefile                        |    6 +
 target-unicore32/Makefile                    |    2 +
 target-xtensa/Makefile                       |    6 +
 xtensa-semi.c => target-xtensa/xtensa-semi.c |    0
 tests/Makefile                               |    1 -
 ui/Makefile                                  |   18 ++
 56 files changed, 674 insertions(+), 620 deletions(-)
 create mode 100644 audio/Makefile
 create mode 100644 block/Makefile
 create mode 100644 bsd-user/Makefile
 create mode 100644 fsdev/Makefile
 create mode 100644 hw/9pfs/Makefile
 create mode 100644 hw/Makefile
 create mode 100644 hw/alpha/Makefile
 create mode 100644 hw/arm/Makefile
 create mode 100644 hw/cris/Makefile
 create mode 100644 hw/i386/Makefile
 create mode 100644 hw/ide/Makefile
 create mode 100644 hw/lm32/Makefile
 create mode 100644 hw/m68k/Makefile
 create mode 100644 hw/microblaze/Makefile
 create mode 100644 hw/mips/Makefile
 create mode 100644 hw/ppc/Makefile
 create mode 100644 hw/s390x/Makefile
 create mode 100644 hw/sh4/Makefile
 create mode 100644 hw/sparc/Makefile
 create mode 100644 hw/sparc64/Makefile
 create mode 100644 hw/usb/Makefile
 create mode 100644 hw/xtensa/Makefile
 create mode 100644 linux-user/Makefile
 create mode 100644 linux-user/arm/nwfpe/Makefile
 create mode 100644 net/Makefile
 create mode 100644 qapi/Makefile
 create mode 100644 qga/Makefile
 create mode 100644 slirp/Makefile
 create mode 100644 target-alpha/Makefile
 create mode 100644 target-arm/Makefile
 rename arm-semi.c => target-arm/arm-semi.c (100%)
 create mode 100644 target-cris/Makefile
 create mode 100644 target-i386/Makefile
 rename ioport-user.c => target-i386/ioport-user.c (100%)
 create mode 100644 target-lm32/Makefile
 create mode 100644 target-m68k/Makefile
 rename m68k-semi.c => target-m68k/m68k-semi.c (100%)
 create mode 100644 target-microblaze/Makefile
 create mode 100644 target-mips/Makefile
 create mode 100644 target-ppc/Makefile
 create mode 100644 target-s390x/Makefile
 create mode 100644 target-sh4/Makefile
 create mode 100644 target-sparc/Makefile
 create mode 100644 target-unicore32/Makefile
 create mode 100644 target-xtensa/Makefile
 rename xtensa-semi.c => target-xtensa/xtensa-semi.c (100%)
 create mode 100644 ui/Makefile

-- 
1.7.10.1