Messages in this thread | | | Date | Wed, 09 Mar 2011 22:43:30 -0800 | From | Darren Hart <> | Subject | Re: [PATCH trace-cmd 3/3] Revert "trace-cmd: Use conditional assignment of CC and AR" |
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On 03/09/2011 06:27 PM, David Sharp wrote: > On Wed, Mar 9, 2011 at 5:58 PM, Darren Hart<dvhart@linux.intel.com> wrote: >> 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. > > It's a little odd that the default CC is "cc" unless you supply > CROSS_COMPILE, then it's "gcc". I'd probably be okay with this, but I > would think it's weird. > > I don't know the answers, but if we take the kernel Makefile as a > template, then setting CC doesn't work.
The kernel is a bit special I believe as it is pretty tied to gcc. Is trace-cmd tied to gcc to such a degree that we want to make it difficult for people to try different compilers?
-- Darren Intel Open Source Technology Center Yocto Project - Linux Kernel
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