[RFC PATCH 0/2] Make host compiler and linker flags modifyable

[RFC PATCH 0/2] Make host compiler and linker flags modifyable

[Markus Mayer]

Being able to pass in extra compiler or linker flags for the host
compiler can be quite helpful. This proposed series would allow a user
to do just that.

Please let me know if you would consider this kind of change for
inclusion or if there is an alternate approach to achieve the same
goal.

Markus Mayer (2):
  Makefile: Make HOSTCFLAGS and HOSTCXXFLAGS user modifyable
  Makefile: Introduce HOSTLDFLAGS environment variable

 Makefile | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

-- 
1.9.1

[RFC PATCH 1/2] Makefile: Make HOSTCFLAGS and HOSTCXXFLAGS user modifyable

[Markus Mayer]

In order to allow the user to pass extra arguments to the host
compiler, we no longer overwrite the host compiler flags in the
makefile, but append them to what was passed in.

Signed-off-by: Markus Mayer <markus.mayer@linaro.org>
---
 Makefile | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Makefile b/Makefile
index 97b2861..5795eea 100644
--- a/Makefile
+++ b/Makefile
@@ -251,8 +251,8 @@ CONFIG_SHELL := $(shell if [ -x "$$BASH" ]; then echo $$BASH; \
 
 HOSTCC       = gcc
 HOSTCXX      = g++
-HOSTCFLAGS   = -Wall -Wmissing-prototypes -Wstrict-prototypes -O2 -fomit-frame-pointer
-HOSTCXXFLAGS = -O2
+HOSTCFLAGS   += -Wall -Wmissing-prototypes -Wstrict-prototypes -O2 -fomit-frame-pointer
+HOSTCXXFLAGS += -O2
 
 ifeq ($(shell $(HOSTCC) -v 2>&1 | grep -c "clang version"), 1)
 HOSTCFLAGS  += -Wno-unused-value -Wno-unused-parameter \
-- 
1.9.1

[RFC PATCH 2/2] Makefile: Introduce HOSTLDFLAGS environment variable

[Markus Mayer]

By default we don't need HOSTLDFLAGS. However, providing it gives the
user the ability to pass extra flags to the host linker should they be
required.

The variables AS LD CC are moved to the next line to keep line length
in check.

Signed-off-by: Markus Mayer <markus.mayer@linaro.org>
---
 Makefile | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Makefile b/Makefile
index 5795eea..f6e2f53 100644
--- a/Makefile
+++ b/Makefile
@@ -414,8 +414,8 @@ KERNELRELEASE = $(shell cat include/config/kernel.release 2> /dev/null)
 KERNELVERSION = $(VERSION)$(if $(PATCHLEVEL),.$(PATCHLEVEL)$(if $(SUBLEVEL),.$(SUBLEVEL)))$(EXTRAVERSION)
 
 export VERSION PATCHLEVEL SUBLEVEL KERNELRELEASE KERNELVERSION
-export ARCH SRCARCH CONFIG_SHELL HOSTCC HOSTCFLAGS CROSS_COMPILE AS LD CC
-export CPP AR NM STRIP OBJCOPY OBJDUMP
+export ARCH SRCARCH CONFIG_SHELL HOSTCC HOSTCFLAGS HOSTLDFLAGS CROSS_COMPILE
+export AS LD CC CPP AR NM STRIP OBJCOPY OBJDUMP
 export MAKE AWK GENKSYMS INSTALLKERNEL PERL UTS_MACHINE
 export HOSTCXX HOSTCXXFLAGS LDFLAGS_MODULE CHECK CHECKFLAGS
 
-- 
1.9.1

Re: [RFC PATCH 1/2] Makefile: Make HOSTCFLAGS and HOSTCXXFLAGS user modifyable

[Sam Ravnborg]

On Fri, Jun 20, 2014 at 11:31:28AM -0700, Markus Mayer wrote:
> In order to allow the user to pass extra arguments to the host
> compiler, we no longer overwrite the host compiler flags in the
> makefile, but append them to what was passed in.
> 
> Signed-off-by: Markus Mayer <markus.mayer@linaro.org>
> ---
>  Makefile | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/Makefile b/Makefile
> index 97b2861..5795eea 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -251,8 +251,8 @@ CONFIG_SHELL := $(shell if [ -x "$$BASH" ]; then echo $$BASH; \
>  
>  HOSTCC       = gcc
>  HOSTCXX      = g++
> -HOSTCFLAGS   = -Wall -Wmissing-prototypes -Wstrict-prototypes -O2 -fomit-frame-pointer
> -HOSTCXXFLAGS = -O2
> +HOSTCFLAGS   += -Wall -Wmissing-prototypes -Wstrict-prototypes -O2 -fomit-frame-pointer
> +HOSTCXXFLAGS += -O2
>  
>  ifeq ($(shell $(HOSTCC) -v 2>&1 | grep -c "clang version"), 1)
>  HOSTCFLAGS  += -Wno-unused-value -Wno-unused-parameter \

With this patch you can only override HOSTCFLAGS.
In many cases appending to the falgs is actually what you want.

Please take a look at how we have implemented it for the kernel with KCFLAGS.
And notice that this is also described in Documentation/kbuild

	Sam

Re: [RFC PATCH 1/2] Makefile: Make HOSTCFLAGS and HOSTCXXFLAGS user modifyable

[Markus Mayer]

On 20 June 2014 11:44, Sam Ravnborg <sam@ravnborg.org> wrote:
> On Fri, Jun 20, 2014 at 11:31:28AM -0700, Markus Mayer wrote:
>> In order to allow the user to pass extra arguments to the host
>> compiler, we no longer overwrite the host compiler flags in the
>> makefile, but append them to what was passed in.
>>
>> Signed-off-by: Markus Mayer <markus.mayer@linaro.org>
>> ---
>>  Makefile | 4 ++--
>>  1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/Makefile b/Makefile
>> index 97b2861..5795eea 100644
>> --- a/Makefile
>> +++ b/Makefile
>> @@ -251,8 +251,8 @@ CONFIG_SHELL := $(shell if [ -x "$$BASH" ]; then echo $$BASH; \
>>
>>  HOSTCC       = gcc
>>  HOSTCXX      = g++
>> -HOSTCFLAGS   = -Wall -Wmissing-prototypes -Wstrict-prototypes -O2 -fomit-frame-pointer
>> -HOSTCXXFLAGS = -O2
>> +HOSTCFLAGS   += -Wall -Wmissing-prototypes -Wstrict-prototypes -O2 -fomit-frame-pointer
>> +HOSTCXXFLAGS += -O2
>>
>>  ifeq ($(shell $(HOSTCC) -v 2>&1 | grep -c "clang version"), 1)
>>  HOSTCFLAGS  += -Wno-unused-value -Wno-unused-parameter \
>
> With this patch you can only override HOSTCFLAGS.
> In many cases appending to the falgs is actually what you want.
>
> Please take a look at how we have implemented it for the kernel with KCFLAGS.
> And notice that this is also described in Documentation/kbuild

Thanks. I am able to do what I need using HOST_EXTRACFLAGS and HOST_LOADLIBES.

-Markus