special developer's folder with sources safe from cleaning

recipes-kernel/linux/linux-xlnx_3.10.bbappend

@@ -11,17 +11,32 @@ SRCREV = "efc27505715e64526653f35274717c0fc56491e3"
 linux-elphel_label= "git://git.code.sf.net/p/elphel/linux-elphel"
 linux-elphel_branch= "master"
 linux-elphel_gitdir= "${WORKDIR}/linux-elphel"
-# To use the latest leave ""
+# To use the latest leave: "" - (=empty)
 linux-elphel_srcrev= ""
 #linux-elphel_srcrev= "0ca36687a400fd9a5c4510295ae5be88aac77fa4"
 
+DEV_DIR ?= "${TOPDIR}/../linux-elphel"
+
 do_fetch_append() {
-    print("Cloninig ${linux-elphel_label}\n")
-    os.system("git clone -b ${linux-elphel_branch} ${linux-elphel_label} ${linux-elphel_gitdir}")
-    os.system("cd ${linux-elphel_gitdir};git checkout ${linux-elphel_srcrev}")
+    if os.path.isdir("${DEV_DIR}"):
+        print("Found DEV_DIR, skipping cloning")
+    else:
+        print("Cloninig ${linux-elphel_label}\n")
+        os.system("git clone -b ${linux-elphel_branch} ${linux-elphel_label} ${linux-elphel_gitdir}")
+        os.system("cd ${linux-elphel_gitdir};git checkout ${linux-elphel_srcrev}")
 }
 
 do_unpack_append() {
-    print("Copying ${linux-elphel_gitdir} over ${S}\n")
-    os.system("cp -rf ${linux-elphel_gitdir}/* ${S}")
+    if os.path.isdir("${DEV_DIR}"):
+        print("DEV_DIR exists - creating links...")
+        devdir_abspath = os.path.abspath("${DEV_DIR}")
+        for path, folders, files in os.walk("${DEV_DIR}"):
+            folders[:]=[fd for fd in folders if fd != ".git"]
+            for filename in files:
+                file_abspath = os.path.abspath(os.path.join(path, filename))
+                file_relpath = file_abspath.replace(devdir_abspath+"/", '')
+                os.system("cd ${S};ln -s "+file_abspath+" "+file_relpath)
+    else:
+        print("Copying ${linux-elphel_gitdir} over ${S}\n")
+        os.system("cp -rf ${linux-elphel_gitdir}/* ${S}")
 }
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