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From: Julien Grall <julien.grall@arm.com>
To: Ian Jackson <Ian.Jackson@eu.citrix.com>
Cc: sstabellini@kernel.org, wei.liu2@citrix.com,
	steve.capper@arm.com, andrew.cooper3@citrix.com,
	xen-devel@lists.xen.org, Wei Chen <wei.chen@linaro.org>
Subject: Re: [RFC] xen/arm: build: add missed dependency for head.S
Date: Tue, 7 Jun 2016 11:07:38 +0100	[thread overview]
Message-ID: <57569CEA.7060005@arm.com> (raw)
In-Reply-To: <22358.39936.692242.613124@mariner.uk.xensource.com>

Hi Ian,

On 07/06/16 11:03, Ian Jackson wrote:
> Julien Grall writes ("Re: [RFC] xen/arm: build: add missed dependency for head.S"):
>> On 03/06/16 11:07, Wei Chen wrote:
>>> When we update the header files that had been included in head.S.
>>> The build system would not re-compile the head.S. Because in the
>>> build rules, the dependencies are setting to .*.d (eg. DEPS = .*.d)
>>> files in the same folder as Makefile.
>>>
>>> But head.S is very special, it was used by the Makefile in the parent
>>> folder: "ALL_OBJS := $(TARGET_SUBARCH)/head.o".
>>>
>>> In this case, the build system could not find the dependency in DEPS.
>>> When we update the header files, the build system is unware of this
>>> update. If we re-build the Xen without doing make clean or touching
>>> the head.S, the build system will not recompile the head.S.
>>>
>>> Signed-off-by: Wei Chen <Wei.Chen@linaro.org>
>
> Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
>
> This should be in 4.7 and is a backport candidate.

Sounds good to me.

>>> In my mind, the better way to fix this bug is converting the DEPS from
>>> ALL_OBJS. But I am afraid of the impact. I am not sure whether there
>>> are some dependencies are not generated from obj files.
>
> I do like this idea but I have the same worry.  It might be possible
> to dump ALL_OBJS out somehow and check this, but it might be
> arch-dependent.

FWIW, Wei sent a new version today [1] which implement his suggestion. 
Although it might be too risky for Xen 4.7.

Regards,

[1] 
http://lists.xenproject.org/archives/html/xen-devel/2016-06/msg00781.html

-- 
Julien Grall

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      parent reply	other threads:[~2016-06-07 10:07 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-06-03 10:07 Wei Chen
2016-06-06 17:08 ` Julien Grall
2016-06-07 10:03   ` Ian Jackson
2016-06-07  4:34     ` [RFC v2] " Wei Chen
2016-06-07 13:18       ` Konrad Rzeszutek Wilk
2016-06-08  3:10         ` Wei Chen
2016-06-07 16:01       ` [RFC v2] xen/arm: build: add missed dependency for head.S [and 1 more messages] Ian Jackson
2016-06-07 16:24         ` Wei Liu
2016-06-08  3:14           ` Wei Chen
2016-06-08  8:09             ` Wei Liu
2016-06-07 10:07     ` Julien Grall [this message]

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