image*.bbclass, kernel*.bbclass: create versioned hard links instead of version-less symlinks

* We used to create the actual artifact files with some version
  in the filename and then created symlink without any version
  which was updated to point to the latest one created.
  In some scenarios it's useful to create all artifacts - typically
  rootfs and kernel images with the same version - like release
  build even when the kernel itself wasn't modified since the
  previous release.

  If we include the release version in the regular _NAME variables
  then we'll need to re-run do_deploy and do_image which will cause
  kernel to be rebuilt and image to be re-created even when the
  only change since last build was the version number.

  With this change we can re-use kernel and image from sstate when
  nothing was changed and run only very fast do_deploy_links task
  which just adds another hard link to existing artifact from
  sstate.

* This is already used by various LGE builds as do_webos_deploy_fixup()
  https://github.com/webosose/meta-webosose/blob/master/meta-webos/classes/webos_deploy.bbclass
  but injecting this task in all the right places id difficult
  and sometimes requires whole bbclass to be duplicated. Having
  simpler way of versioning artifacts directly in oe-core might
  be useful for others.

* move IMAGE_VERSION_SUFFIX from _NAME variables to _LINK_NAME
  that way e.g. kernel.do_deploy can be reused from sstate to
  provide "version-less" artifacts and then very fast
  do_deploy_links task just adds links with consistent suffixes
  (by default the version from the recipe but could be easily set
  to e.g. some release name when building some products).
* create hard links instead of symlinks, so that whatever version
  the filename says is really there
* some IMAGE_FSTYPES might need the "version-less" IMAGE_NAME file
  to be removed first or they might either append or update the
  content of the image instead of creating new image file from
  scratch - I have seen this only with one proprietary format we
  generate with our own tool, so hopefully this isn't very common
* this is basically the mechanism are using in webOS with
  WEBOS_IMAGE_NAME_SUFFIX which is for official builds set from
  jenkins job and then all artifacts (images as well as corresponding
  kernel files) have the same version string)

* without this, you can still easily set the variables to contain
  the version from jenkins job (excluded from sstate signature like
  DATETIME currently is to prevent rebuilding it everytime even when
  the content didn't change) but then when kernel is reused from sstate
  you can have version 1.0 used on kernel artifacts and 2.0 on image
  artifacts.

* if you don't exclude the version string with vardepsexclude, then
  you get the right version in the filenames but for cost of
  re-executing do_deploy every single time, which with rm_work will
  cause all kernel tasks to be re-executed (together with everything
  which depends on it like external modules etc).

* the implementation "from outside" is a bit tricky as shown in webOS
  OSE, because first you need to reverse the meaning of IMAGE_NAME
  and IMAGE_LINK_NAME like here, but also replace all symlinks with
  hardlinks and then adjust all recipes/bbclasses to depend on our
  do_deploy_fixup task instead of the original do_deploy
  see the variable modifications:
  https://github.com/webosose/meta-webosose/blob/a35e81622aae1066591e44a132d01297ff478248/meta-webos/conf/distro/include/webos.inc#L65
  and then various bbclasses to hook do_webos_deploy_fixup task creating
  the hardlinks for possible artifacts:
  https://github.com/webosose/meta-webosose/blob/a35e81622aae1066591e44a132d01297ff478248/meta-webos/classes/webos_deploy.bbclass
  https://github.com/webosose/meta-webosose/blob/a35e81622aae1066591e44a132d01297ff478248/meta-webos/classes/kernel.bbclass
  https://github.com/webosose/meta-webosose/blob/a35e81622aae1066591e44a132d01297ff478248/meta-webos/classes/image.bbclass
  so hopefully with all these changes in oe-core other project can
  achieve the same just by setting one variable IMAGE_VERSION_SUFFIX

* drop ${PKGE}-${PKGV}-${PR} from kernel artifacts names (this is the
  latest build) and add it only in hardlinks created in do_deploy_links
  so that we can use PKGR there again (because these links are generally
  used only by human operators and they don't have their own TASKHASH or
  the IMAGE_VERSION_SUFFIX might be set to some release name which they
  do understand

* this allows to drop package_get_auto_pr from kernel do_deploy as well,
  leaving only 2 EXTENDPRAUTO bumps for each kernel build (do_package
  and do_deploy_links, unfortunatelly these will still have different
  value, so if you're looking for the exact kernel image in deploy
  directory based on kernel image package version seen on the device the
  EXTENDPRAUTO part of PR will be different).

[YOCTO #12937]

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>

1 files changed, 5 insertions, 5 deletions

diff --git a/meta/classes/image.bbclass b/meta/classes/image.bbclass
index c2f3232027..bf271ef501 100644
--- a/meta/classes/image.bbclass
+++ b/meta/classes/image.bbclass
@@ -589,14 +589,14 @@ python create_symlinks() {
         return
     for type in subimages:
         dst = os.path.join(deploy_dir, link_name + "." + type)
-        src = img_name + imgsuffix + type
-        if os.path.exists(os.path.join(deploy_dir, src)):
-            bb.note("Creating symlink: %s -> %s" % (dst, src))
+        src = os.path.join(deploy_dir, img_name + imgsuffix + type)
+        if os.path.exists(src):
+            bb.note("Creating hardlink: %s -> %s" % (dst, src))
             if os.path.islink(dst):
                 os.remove(dst)
-            os.symlink(src, dst)
+            os.link(src, dst)
         else:
-            bb.note("Skipping symlink, source does not exist: %s -> %s" % (dst, src))
+            bb.note("Skipping hardlink, source does not exist: %s -> %s" % (dst, src))
 }
 
 MULTILIBRE_ALLOW_REP =. "${base_bindir}|${base_sbindir}|${bindir}|${sbindir}|${libexecdir}|${sysconfdir}|${nonarch_base_libdir}/udev|/lib/modules/[^/]*/modules.*|"