Re: [Minios-devel] [UNIKRAFT PATCHv4 05/43] build: Add a makefile function to check GCC version

[Simon Kuenzer <simon.kuenzer@xxxxxxxxx>]

I just noticed that this check is not working if you compare 4.9 (older) 
with 4.10 (newer) because 4.10 is considered as the floating point 
number 4.1 by `bc`. As fix we probably should do two individual checks: 
(1) major and then (2) minor.
Btw, do you think you could provide a version that does not need `bc`? I 
rather prefer something that requires the least possible tools installed 
on the system. My concern is that we can't assume `bc` is installed as a 
standard tool. But maybe I am wrong with this concern. What do you think?
On 06.07.2018 11:03, Wei Chen wrote:
> In this patch, we add a test_gcc_version function to test GCC
> version and return a result. In this case, this function can
> be used not only for processor flags check, but also can be
> used in other places of Unikraft.
>
> Signed-off-by: Wei Chen <Wei.Chen@xxxxxxx>
> ---
>   Makefile                     | 4 ++++
>   support/build/Makefile.rules | 5 +++++
>   2 files changed, 9 insertions(+)
>
> diff --git a/Makefile b/Makefile
> index d10f53b..e133039 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -428,6 +428,10 @@ LIFTOFF            := liftoff -e -s
>   override ARFLAGS:= rcs
>   CC_VERSION    := $(shell $(CC) --version | \
>                    sed -n -r 's/^.* ([0-9]*)\.([0-9]*)\.([0-9]*)[ ]*.*/\1.\2/p')
> +# Retrieve GCC major and minor number from CC_VERSION. They would be used
> +# to select correct optimization parameters for target CPUs.
> +CC_VER_MAJOR   := $(word 1,$(subst ., ,$(CC_VERSION)))
> +CC_VER_MINOR   := $(word 2,$(subst ., ,$(CC_VERSION)))
>   
>   ASFLAGS		+= -DCC_VERSION=$(CC_VERSION)
>   CFLAGS                += -DCC_VERSION=$(CC_VERSION)
> diff --git a/support/build/Makefile.rules b/support/build/Makefile.rules
> index e317e3d..d5372cd 100644
> --- a/support/build/Makefile.rules
> +++ b/support/build/Makefile.rules
> @@ -29,6 +29,11 @@ lc = $(subst A,a,$(subst B,b,$(subst C,c,$(subst D,d,$(subst 
> E,e,$(subst F,f,$(s
>   # upper case
>   uc = $(subst a,A,$(subst b,B,$(subst c,C,$(subst d,D,$(subst e,E,$(subst 
> f,F,$(subst g,G,$(subst h,H,$(subst i,I,$(subst j,J,$(subst k,K,$(subst 
> l,L,$(subst m,M,$(subst n,N,$(subst o,O,$(subst p,P,$(subst q,Q,$(subst 
> r,R,$(subst s,S,$(subst t,T,$(subst u,U,$(subst v,V,$(subst w,W,$(subst 
> x,X,$(subst y,Y,$(subst z,Z,$(1)))))))))))))))))))))))))))
>   
> +# test whether GCC version meets the minimum requirement
> +# test_gcc_version $gcc_major,$gcc_minor
> +define test_gcc_version =
> +$(shell echo 'if($(CC_VER_MAJOR).$(CC_VER_MINOR)>=$(1).$(2)) print "y"'| bc)
> +endef
>   
>   ################################################################################
>   #
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