[U-Boot] [PATCH 2/2] SPL: Allow ARM926EJS to avoid compiling in the CPU support code

[Marek Vasut <marek.vasut@gmail.com>]

On Saturday, October 22, 2011 02:04:52 AM Tom Rini wrote:
> On Fri, Oct 21, 2011 at 4:45 PM, Marek Vasut <marek.vasut@gmail.com> wrote:
> > On Saturday, October 22, 2011 01:08:43 AM Albert ARIBAUD wrote:
> >> Le 22/10/2011 00:46, Marek Vasut a ?crit :
> >> > On Saturday, October 22, 2011 12:44:06 AM Albert ARIBAUD wrote:
> >> >> Le 22/10/2011 00:00, Marek Vasut a ?crit :
> >> >>> On Friday, October 21, 2011 11:52:23 PM Albert ARIBAUD wrote:
> >> >>>> Hi Marek,
> >> >>>> 
> >> >>>> Le 21/10/2011 22:44, Marek Vasut a ?crit :
> >> >>>>> On Thursday, October 06, 2011 02:13:26 AM Marek Vasut wrote:
> >> >>>>>> This allows the SPL to avoid compiling in the CPU support code.
> >> >>>>>> 
> >> >>>>>> Signed-off-by: Marek Vasut<marek.vasut@gmail.com>
> >> >>>>>> Cc: Stefano Babic<sbabic@denx.de>
> >> >>>>>> Cc: Wolfgang Denk<wd@denx.de>
> >> >>>>>> Cc: Detlev Zundel<dzu@denx.de>
> >> >>>>>> Cc: Scott Wood<scottwood@freescale.com>
> >> >>>>>> ---
> >> >>>>>> 
> >> >>>>>>     arch/arm/cpu/arm926ejs/Makefile |    7 +++++++
> >> >>>>>>     1 files changed, 7 insertions(+), 0 deletions(-)
> >> >>>>>> 
> >> >>>>>> diff --git a/arch/arm/cpu/arm926ejs/Makefile
> >> >>>>>> b/arch/arm/cpu/arm926ejs/Makefile index 930e0d1..3f9b0f1 100644
> >> >>>>>> --- a/arch/arm/cpu/arm926ejs/Makefile
> >> >>>>>> +++ b/arch/arm/cpu/arm926ejs/Makefile
> >> >>>>>> @@ -28,6 +28,13 @@ LIB = $(obj)lib$(CPU).o
> >> >>>>>> 
> >> >>>>>>     START      = start.o
> >> >>>>>>     COBJS      = cpu.o
> >> >>>>>> 
> >> >>>>>> +ifdef CONFIG_SPL_BUILD
> >> >>>>>> +ifdef CONFIG_SPL_NO_CPU_SUPPORT_CODE
> >> >>>>>> +START :=
> >> >>>>>> +COBJS :=
> >> >>>>>> +endif
> >> >>>>>> +endif
> >> >>>>>> +
> >> >>>>>> 
> >> >>>>>>     SRCS       := $(START:.o=.S) $(SOBJS:.o=.S) $(COBJS:.o=.c)
> >> >>>>>>     OBJS       := $(addprefix $(obj),$(COBJS) $(SOBJS))
> >> >>>>>>     START      := $(addprefix $(obj),$(START))
> >> >>>>> 
> >> >>>>> Hi Albert,
> >> >>>>> 
> >> >>>>> can we get this applied please?
> >> >>>> 
> >> >>>> I still don't understand what this is supposed to do -- why not
> >> >>>> linking this code is required.
> >> >>>> 
> >> >>>> Amicalement,
> >> >>> 
> >> >>> Hi Albert,
> >> >>> 
> >> >>> I use very different start.S in SPL. And I don't need cpu.o at all.
> >> >> 
> >> >> That I understand; but is there a /problem/ in linking cpu.o in?
> >> > 
> >> > I suppose it'll be optimized out at link time ?
> >> 
> >> That indirectly answers my question: what you want to achieve is
> >> removing dead code.
> > 
> > The code IS USED in U-Boot, but IS NOT USED in SPL !
> 
> Right, but linked and unused code in SPL is (or should be!) thrown
> away, is what's
> trying to be driven home right now.  If the file is going to go away,
> and it's compiled
> thrown away at final link of SPL, lets just ignore that it exists for
> a little longer, and
> then it won't.

My distrust towards compiler abilities to optimize such stuff out tells me it's 
better to avoid it even to be compiled in at all.