infra/pkg-kconfig: fix saving the config file

PATCH New Yann E. MORIN 3 participants 3 messages Oct 20, 2014 – Oct 22, 2014

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Yann E. MORIN

author

2014-10-20 20:23 UTC #0 lore raw

PATCH 1/1 infra/pkg-kconfig: fix saving the config file

When saving (aka updating) the configuration file of a kconfig package, a subsequent call to "make" would rebuild the package, even though the configuration did not actually change.

It took quite a while to understand why. But the reason is so simple and obvious, when you think about it:

- $(@D)/.config depends on the config file $(BUSYBOX_CONFIG_FILE)
- busybox-update-config then copies $(@D)/.config back to the config

    file $(BUSYBOX_CONFIG_FILE)

- so the config file is newer than $(@D)/.config

So, in the next run, pkg-kconfig believes that it has to rebuild busybox. Bummer... :-/

So, the fix is very trivial, and just requires asking "cp" to preserve timestamps, so the dependency does not kick in at the next run.

Signed-off-by "Yann E. MORIN" <[email protected]>

Cc Thomas De Schampheleire <[email protected]>

---
 package/pkg-kconfig.mk | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

package/pkg-kconfig.mk +1 -1

index 071153a..ec58d69 100644
@@ -66,7 +66,7 @@ $$(addprefix $(1)-,$$($(2)_KCONFIG_EDITORS)): $$($(2)_DIR)/.stamp_kconfig_fixup_
 
 # Target to copy back the configuration to the source configuration file
 $(1)-update-config: $$($(2)_DIR)/.stamp_kconfig_fixup_done
-	cp -f $$($(2)_DIR)/.config $$($(2)_KCONFIG_FILE)
+	cp --preserve=timestamps -f $$($(2)_DIR)/.config $$($(2)_KCONFIG_FILE)
 
 endef # inner-kconfig-package

Signature · 1 line

1.9.1

Thomas De Schampheleire

2014-10-22 08:53 UTC #1 lore raw

PATCH 1/1 infra/pkg-kconfig: fix saving the config file

Quoted 12 lines · Yann E. MORIN

When saving (aka updating) the configuration file of a kconfig package, a subsequent call to "make" would rebuild the package, even though the configuration did not actually change.
It took quite a while to understand why. But the reason is so simple and obvious, when you think about it:
- $(@D)/.config depends on the config file $(BUSYBOX_CONFIG_FILE)
- busybox-update-config then copies $(@D)/.config back to the config
    file $(BUSYBOX_CONFIG_FILE)
- so the config file is newer than $(@D)/.config

Quoted 8 lines

So, in the next run, pkg-kconfig believes that it has to rebuild busybox. Bummer... :-/
So, the fix is very trivial, and just requires asking "cp" to preserve timestamps, so the dependency does not kick in at the next run.
Signed-off-by "Yann E. MORIN" <[email protected]>
Cc Thomas De Schampheleire <[email protected]>

Reviewed-by Thomas De Schampheleire <[email protected]>

Thomas Petazzoni

Applied

2014-10-22 20:51 UTC #2 lore raw

PATCH 1/1 infra/pkg-kconfig: fix saving the config file

In reply to Yann E. MORIN

Dear Yann E. MORIN,

Quoted 12 lines · Yann E. MORIN

When saving (aka updating) the configuration file of a kconfig package, a subsequent call to "make" would rebuild the package, even though the configuration did not actually change.
It took quite a while to understand why. But the reason is so simple and obvious, when you think about it:
- $(@D)/.config depends on the config file $(BUSYBOX_CONFIG_FILE)
- busybox-update-config then copies $(@D)/.config back to the config
    file $(BUSYBOX_CONFIG_FILE)
- so the config file is newer than $(@D)/.config

Quoted 8 lines

So, in the next run, pkg-kconfig believes that it has to rebuild busybox. Bummer... :-/
So, the fix is very trivial, and just requires asking "cp" to preserve timestamps, so the dependency does not kick in at the next run.
Signed-off-by "Yann E. MORIN" <[email protected]>
Cc Thomas De Schampheleire <[email protected]>

Applied, thanks.

Thomas

Signature · 3 lines

Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com