[U-Boot,3/5] kbuild: use $(call cmd, ) rather than $(call if_changed, ) where possible

These build commands are constant (mostly, just concatenating images,
or just copying).  No need to use $(call if_changed,...) for them.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
---

 Makefile             | 26 +++++++++++++-------------
 scripts/Makefile.spl |  4 ++--
 2 files changed, 15 insertions(+), 15 deletions(-)

Hello Masahiro,

On Wed,  3 Feb 2016 21:05:12 +0900, Masahiro Yamada
<yamada.masahiro@socionext.com> wrote:
> These build commands are constant (mostly, just concatenating images,
> or just copying).  No need to use $(call if_changed,...) for them.

I am a total kbuild ignorant, so I'm probably asking a stupid question,
but hey.

What are the exact semantics of $(call if_changed,)? I thought it meant
"call the function if any of the dependencies has changed. If it does,
then won't this patch make the corresponding action systematic, causing
unneeded concatenations or copies?

Amicalement,

Hello Albert,

On Wed, 3 Feb 2016 13:18:35 +0100, Albert ARIBAUD
<albert.u.boot@aribaud.net> wrote:
> Hello Masahiro,
> 
> On Wed,  3 Feb 2016 21:05:12 +0900, Masahiro Yamada
> <yamada.masahiro@socionext.com> wrote:
> > These build commands are constant (mostly, just concatenating images,
> > or just copying).  No need to use $(call if_changed,...) for them.
> 
> I am a total kbuild ignorant, so I'm probably asking a stupid question,
> but hey.
> 
> What are the exact semantics of $(call if_changed,)? I thought it meant
> "call the function if any of the dependencies has changed. If it does,
> then won't this patch make the corresponding action systematic, causing
> unneeded concatenations or copies?

NVM, the answer could be found in later patches in the series.

Amicalement,

On 02/03/2016 05:05 AM, Masahiro Yamada wrote:
> These build commands are constant (mostly, just concatenating images,
> or just copying).  No need to use $(call if_changed,...) for them.

I disagree, since I believe this change means that if someone /does/ 
change the command in the future (e.g. to replace it with more complex 
processing, or add additional dependencies), then the Makefile will/may 
not automatically rebuild those targets, which is the entire point of 
using if_changed, and is a huge benefit of using Kbuild.

In my opinion, every rule should use if_changed, and contain a single 
command at the Makefile level; i.e. I noticed the following somewhere, 
which also doesn't rebuild the target in all cases if the commands are 
changed, which is bad:

target: sources FORCE
     $(call if_changed,xxx)
     something_else
     yet_more_cmds

If "something_else" or "yet_more_cmds" are edited, the target won't get 
rebuilt unless some other modification causes it to be.

Hi Stephen,


2016-02-04 0:57 GMT+09:00 Stephen Warren <swarren@wwwdotorg.org>:
> On 02/03/2016 05:05 AM, Masahiro Yamada wrote:
>>
>> These build commands are constant (mostly, just concatenating images,
>> or just copying).  No need to use $(call if_changed,...) for them.
>
>
> I disagree, since I believe this change means that if someone /does/ change
> the command in the future (e.g. to replace it with more complex processing,
> or add additional dependencies), then the Makefile will/may not
> automatically rebuild those targets, which is the entire point of using
> if_changed, and is a huge benefit of using Kbuild.

I do not a strong opinion about this, so
I will drop 3/5 and submit v2.



> In my opinion, every rule should use if_changed, and contain a single
> command at the Makefile level; i.e. I noticed the following somewhere, which
> also doesn't rebuild the target in all cases if the commands are changed,
> which is bad:
>
> target: sources FORCE
>     $(call if_changed,xxx)
>     something_else
>     yet_more_cmds
>
> If "something_else" or "yet_more_cmds" are edited, the target won't get
> rebuilt unless some other modification causes it to be.

Patch are welcome to clean up them.

On Fri, 2016-02-05 at 14:33 +0900, Masahiro Yamada wrote:
> >> These build commands are constant (mostly, just concatenating
> images,
> >> or just copying).  No need to use $(call if_changed,...) for them.
> >
> >
> > I disagree, since I believe this change means that if someone /does/ change
> > the command in the future (e.g. to replace it with more complex processing,
> > or add additional dependencies), then the Makefile will/may not
> > automatically rebuild those targets, which is the entire point of using
> > if_changed, and is a huge benefit of using Kbuild.
> 
> I do not a strong opinion about this, so
> I will drop 3/5 and submit v2.

I think the same logic applies to that part of the change in patch 2 as
well.

Ian.