[Xen-changelog] [xen master] stubdom: modify ioemu linkfarm only if necessary

[patchbot@xxxxxxx]

commit 0738d6fe7116cc2398bcb557c957ab38b712fe96
Author:     Juergen Gross <jgross@xxxxxxxx>
AuthorDate: Tue Dec 13 16:38:06 2016 +0100
Commit:     Wei Liu <wei.liu2@xxxxxxxxxx>
CommitDate: Wed Dec 14 14:42:02 2016 +0000

    stubdom: modify ioemu linkfarm only if necessary
    
    Several stubdom libraries are being rebuilt each time a top level make
    is called as they depend on stubdom/ioemu/linkfarm.stamp which is
    depending on tools/qemu-xen-traditional-dir. Unfortunately this
    directory is modified by each "make tools" call.
    
    This can be avoided by writing stubdom/ioemu/linkfarm.stamp only if
    a source file beneath tools/qemu-xen-traditional-dir has been added
    or removed.
    
    Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
    Acked-by: Wei Liu <wei.liu2@xxxxxxxxxx>
    Reviewed-by: Samuel Thibault <samuel.thibault@xxxxxxxxxxxx>
---
 stubdom/Makefile | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/stubdom/Makefile b/stubdom/Makefile
index bc49cfe..f858210 100644
--- a/stubdom/Makefile
+++ b/stubdom/Makefile
@@ -298,9 +298,13 @@ ioemu/linkfarm.stamp: 
$(XEN_ROOT)/tools/qemu-xen-traditional-dir
        (cd $$src && find *     ! -type l  -type f  $(addprefix ! -name ,       
\
                        '*.[oda1]' 'config-*' config.mak qemu-dm qemu-img-xen   
\
                        '*.html' '*.pod'                                        
\
-                       )) |                                                    
\
-           while read f; do rm -f "$$f"; ln -s "$$src/$$f" "$$f"; done
-       touch ioemu/linkfarm.stamp
+                       )) >linkfarm.stamp.tmp;                         \
+       cmp -s linkfarm.stamp.tmp linkfarm.stamp &&                     \
+               rm linkfarm.stamp.tmp || {                              \
+               mv linkfarm.stamp.tmp linkfarm.stamp;                   \
+               cat linkfarm.stamp | while read f;                      \
+                       do rm -f "$$f"; ln -s "$$src/$$f" "$$f"; done;  \
+       }
 else
 export QEMU_ROOT
 
--
generated by git-patchbot for /home/xen/git/xen.git#master

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