[yocto] bitbake-whatchanged usefulness?

[Gary Thomas]

I just updated my Poky/Yocto master and tried to use bitbake-whatchanged
to see what was about to happen.  I'm not sure I know how to
read this and there doesn't seem to be any documentation other
than the simple help provided by the script.

Here's part of what I saw:
-------------------------------------------------
=== Newly added tasks: (87 tasks)
   ninja-native: do_compile do_configure do_patch do_unpack do_install
   ldconfig-native: do_patch do_configure do_unpack do_compile do_install
   makedevs-native: do_install do_patch do_unpack do_compile do_configure
   python: do_populate_sysroot do_package do_fetch do_packagedata do_patch do_build do_configure do_compile do_install do_package_write_ipk do_unpack do_populate_lic do_package_qa
   unzip-native: do_compile do_unpack do_configure do_install do_patch
   gettext-minimal-native: do_configure do_install do_patch do_unpack do_compile
   perl-native: do_configure do_compile do_install do_unpack do_patch
   update-rc.d-native: do_install do_unpack do_patch do_configure do_compile
   texinfo-dummy-native: do_unpack do_compile do_patch do_configure do_install
   gnu-config-native: do_compile do_unpack do_install do_configure do_patch
   sgmlspl-native: do_patch do_install do_configure do_compile do_unpack
   u-boot-mkimage-native: do_configure do_patch do_compile do_unpack do_install
   imx6-demo-image: do_configure do_populate_lic do_compile do_install
   opkg-utils-native: do_configure do_install do_unpack do_compile do_patch
   cryptodev-linux-native: do_unpack do_install do_patch do_configure do_compile
   dosfstools-native: do_patch do_install do_unpack do_compile do_configure

=== PV changed: (57 tasks)
   linux-libc-headers: 3.17.7 -> 3.19
   quilt-native: 0.63 -> 0.64
   cups: 2.0.1 -> 2.0.2
   pulseaudio: 5.0 -> 6.0
   kern-tools-native: 0.2+gitAUTOINC+daab4442c2 -> 0.2+gitAUTOINC+cab17f8849

=== Dependencies changed: (3101 tasks)
   speex: do_package do_package_qa do_packagedata do_populate_lic do_package_write_ipk do_compile do_configure do_populate_sysroot do_build do_install
   busybox: do_patch do_unpack do_build do_configure do_packagedata do_package_write_ipk do_populate_sysroot do_package_qa do_package do_fetch do_install do_compile do_populate_lic
   ...

=== Summary: (3245 changed, 1721 unchanged)
Newly added: 87
PV changed: 57
PR changed: 0
Dependencies changed: 3101
-------------------------------------------------

A couple of questions:

* I know that python was updated from 2.7.3 to 2.7.9 - why doesn't
   it show in the 'PV changed' section?
* If there were 57 PV changes, why did only 5 get shown?
* How can I tell what dependencies were changed - that section doesn't
   really tell me much more than certain recipes will have to be rebuilt
   because some dependency changed.

Is there anything [more] useful that I can get from this tool?

-- 
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Gary Thomas                 |  Consulting for the
MLB Associates              |    Embedded world
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