[U-Boot] Compiling fw_printenv tool

[Detlev Zundel]

Hi Masahiro-san,

>> > How do I cross compile it for my embedded system? Do I just set the
>> > HOSTCC environment variable in the Makefile?
>> 
>> No changes in any makefiles are needed, just do
>> 
>> make HOSTCC=arm-none-linuex-gnueabi-gcc env
>
> It looks weird to me.

You're not alone actually :) In a land far away in time, we used to
always cross-compile this tool.  But at a certain stage IIRC Mike
Frysinger convinced us that this tool should be compiled with the host
toolchain instead (honestly, I can't remember why).  So we accepted this
and documented it a later commit log:

commit 02bd475e343582b3c915b94ef4016d5876d4a4f1
Author: Daniel Hobi <daniel.hobi at schmid-telecom.ch>
Date:   Wed Nov 10 14:11:21 2010 +0100

    tools/env: cleanup host build flags
    
    This patch makes tools/env/Makefile more similar to tools/imls:
    - define HOSTSRCS and HOSTCPPFLAGS, so that .depend generation works.
    - include U-Boot headers using -idirafter to prevent picking up
      u-boot/include/errno.h.
    - use HOSTCFLAGS_NOPED (fw_env.c does not conform to -pedantic).
    
    In order to cross-compile tools/env, override the HOSTCC variable
    as in this example:
    
      make tools env HOSTCC=bfin-uclinux-gcc
    
    Signed-off-by: Daniel Hobi <daniel.hobi at schmid-telecom.ch>
    Tested-by: Detlev Zundel <dzu at denx.de>
    Tested-by: Steve Sakoman <steve.sakoman at linaro.org>

I for myself only "saved" the magic invocation needed and forgot the
reasoning...

> I think HOSTCC should be always "gcc".

Correct.  One should only switch this for one specific build target.

> In my understanding,  tools/env/fw_printenv is not a host program
> but a one for the target embedded Linux.

Correct.

> Is there any reason that we don't fix tools/env/Makefile?
>
>   $(obj)fw_printenv:      $(HOSTSRCS) $(HEADERS)
>           $(HOSTCC) $(HOSTCFLAGS_NOPED) $(HOSTLDFLAGS) -o $@ $(HOSTSRCS)
>           $(HOSTSTRIP) $@
>
> to
>
>   $(obj)fw_printenv:      $(HOSTSRCS) $(HEADERS)
>           $(CC) $(HOSTCFLAGS_NOPED) $(HOSTLDFLAGS) -o $@ $(HOSTSRCS)
>           $(STRIP) $@

Personally I think I can now remember that the change was mostly done to
get the makefile somehow "more similar" to other makefiles.  So
considering your massive (and most welcome!) work on the build
infrastructure, I think you have become kind of an unspoken authority on
these issues ;) So if it helps in your cleanup and nobody objects, I'll
ack your changes.

Best wishes
  Detlev

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