Re: [PATCH trace-cmd 3/3] Revert "trace-cmd: Use conditional assignmentof CC and AR"

[Darren Hart]

On 03/09/2011 05:36 PM, Steven Rostedt wrote:
> On Wed, 2011-03-09 at 17:27 -0800, Darren Hart wrote:
> > On 03/09/2011 03:58 PM, David Sharp wrote:
> > > This reverts commit 6c696cec3f264a9399241b6e648f58bc97117d49.
> > >
> > > Make has default values CC and AR of 'cc' and 'ar' respectively. This means
> > > that "CC ?= anything" will never have effect, because CC is always already set.
> > > Because of this, 6c696cec makes setting CROSS_COMPILE from the command line or
> > > environment useless.
> >
> > The problem with this approach is it prevents the user from setting CC
> > explicitly with the environment which is a very common way of using a
> > specific version of gcc (for example). It also places restrictions on
> > the filename of the compiler (it must end in gcc - so gcc-4.5.1 cannot
> > work), this isn't acceptable.
> >
> > You could use CC=your-cross-compiler, and if that doesn't work for you,
> > you could prepare a patch that conditionally sets CC only if
> > CROSS_COMPILE is set, but please do not simply revert this patch which
> > solved a real problem with the Makefile.
>
> Hmm, but the thing is, the change did not work,

It did work for me as I was setting CC= on the command line.

unless your environment
> for some reason does not supply a 'cc'. Or that 'cc' defaulted to the
> compiler that you wanted, where 'gcc' would not.
>
> Thus, would you be fine with something like:
>
> 	BUILD_CC ?=	$(CROSS_COMPILE)gcc
> 	CC	 =	$(BUILD_CC)

This would also work, but what is wrong with:

dvhart@doubt:templates$ cat Makefile
ifdef CROSS_COMPILE
CC = $(CROSS_COMPILE)gcc
AR = $(CROSS_COMPILE)ar
endif

all:
	echo "CC: $(CC)"

dvhart@doubt:templates$ make -s
CC: cc

dvhart@doubt:templates$ CC=gcc-4.5.1 make -s
CC: gcc-4.5.1

dvhart@doubt:templates$ CROSS_COMPILE=my-cross- make -s
CC: my-cross-gcc


Seems to meet everyone's needs without changing any tools/scripts/etc 
that have used trace-cmd before or after the CC ?= wreckage.



Thanks,

--
Darren

> Then you could just update BUILD_CC and that will update CC for you.
>
> -- Steve


--
Darren Hart
Intel Open Source Technology Center
Yocto Project - Linux Kernel
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