[PATCH v2] kernel-yocto: checksum all modifications to available kernel fragments directories

["Bruce Ashfield" <bruce.ashfield@gmail.com>]

From: Bruce Ashfield <bruce.ashfield@gmail.com>

This is based on the patch from Zhaolong Zhang <zhangzl2013@126.com>
[kernel-yocto: checksum indirect cfg and scc files]

While the recommended manner to share/reuse feature fragments is to
maintain them in a kernel-meta repository and track the changes via the
standard SRCREV fetcher mechanism, that method is not always practical
for small sets of features or for quick testing of changes.

These other flows use .scc files on the SRC_URI. It has been noted that
config fragments or other features indirectly included by those .scc
files will not trigger the kernel meta-data to be re-run and hence a
build can continue with stale data (or not be triggered at all).

To solve this issue, we can collect the directories that are searchable
via FILESEXTRAPATHS and add them to the do_kernel_metadata task
checksum.

This allows modifications, additions and removals from the potential
kernel feature directories to trigger a re-execution of the meta data
task.

Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>
---

v2: at Richard's suggestion, the searching function is simplified to
    not use os.walk(). This has the potential of adding some directories
    that don't have .cfg and .scc files to the checksum, but that won't
    add signficant re-executions of the task.

 meta/classes/kernel-yocto.bbclass | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/meta/classes/kernel-yocto.bbclass b/meta/classes/kernel-yocto.bbclass
index 96ea612258..c6a128ebfe 100644
--- a/meta/classes/kernel-yocto.bbclass
+++ b/meta/classes/kernel-yocto.bbclass
@@ -85,6 +85,21 @@ def get_machine_branch(d, default):
 	    
     return default
 
+# returns a list of all directories that are on FILESEXTRAPATHS (and
+# hence available to the build) that contain .scc or .cfg files
+def get_dirs_with_fragments(d):
+    extrapaths = []
+    extrafiles = []
+    extrapathsvalue = (d.getVar("FILESEXTRAPATHS") or "")
+    # Remove default flag which was used for checking
+    extrapathsvalue = extrapathsvalue.replace("__default:", "")
+    extrapaths = extrapathsvalue.split(":")
+    for path in extrapaths:
+        if path + ":True" not in extrafiles:
+            extrafiles.append(path + ":" + str(os.path.exists(path)))
+
+    return " ".join(extrafiles)
+
 do_kernel_metadata() {
 	set +e
 
@@ -367,6 +382,7 @@ do_kernel_checkout[dirs] = "${S}"
 addtask kernel_checkout before do_kernel_metadata after do_symlink_kernsrc
 addtask kernel_metadata after do_validate_branches do_unpack before do_patch
 do_kernel_metadata[depends] = "kern-tools-native:do_populate_sysroot"
+do_kernel_metadata[file-checksums] = " ${@get_dirs_with_fragments(d)}"
 do_validate_branches[depends] = "kern-tools-native:do_populate_sysroot"
 
 do_kernel_configme[depends] += "virtual/${TARGET_PREFIX}binutils:do_populate_sysroot"
-- 
2.19.1