Date: Sat, 28 Oct 2017 13:11:59 +0200 From: Dimitry Andric <dim@FreeBSD.org> To: =?utf-8?Q?Eddy_Petri=C8=99or?= <eddy.petrisor@gmail.com> Cc: freebsd-toolchain@freebsd.org, freebsd-arm@freebsd.org Subject: Re: lib/clan/llvm.build.mk: Shouldn't BUILD_TRIPLE definition rely host 'cc -dumpmachine'? Message-ID: <CDAA0CB5-F1FC-40FE-AEC5-56FD64654671@FreeBSD.org> In-Reply-To: <CAK0XTWczya8vg_sQZPqz-ZyYZRMq1v6p%2Bjs90S%2BjaDHxo2=1gA@mail.gmail.com> References: <CAK0XTWczya8vg_sQZPqz-ZyYZRMq1v6p%2Bjs90S%2BjaDHxo2=1gA@mail.gmail.com>
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On 27 Oct 2017, at 08:23, Eddy Petrișor <eddy.petrisor@gmail.com> wrote:
>
> I am trying to make the FreeBSD code base build from a Linux host and
> found this bit which defines BUILD_TRIPLE in a way which to my
> untrained eyes look like overengineering.
>
> .if ${TARGET_ARCH:Marmv6*} && (!defined(CPUTYPE) || ${CPUTYPE:M*soft*} == "")
> TARGET_ABI= -gnueabihf
> .elif ${TARGET_ARCH:Marm*}
> TARGET_ABI= -gnueabi
> .else
> TARGET_ABI=
> .endif
> VENDOR= unknown
> OS_VERSION= freebsd12.0
>
> TARGET_TRIPLE?=
> ${TARGET_ARCH:C/amd64/x86_64/:C/arm64/aarch64/}-${VENDOR}-${OS_VERSION}${TARGET_ABI}
> BUILD_TRIPLE?=
> ${BUILD_ARCH:C/amd64/x86_64/:C/arm64/aarch64/}-${VENDOR}-${OS_VERSION}
I don't see much overengineering here? :) We simply trust BUILD_ARCH,
as it is passed in by the top-level Makefile.inc1. This is how most of
these down-level Makefiles work. Running all kinds of commands to
figure out architectures and the like should be avoided in such
Makefiles.
> To support a Linux host I made these changes that is using 'cc
> -dumpmachine' to get the correct BUILD_TRIPLE,
Unfortunately, this is the wrong option to do so. The gcc manual says:
-dumpmachine
Print the compiler’s target machine (for example, ‘i686-pc-linux-gnu’)
-and don’t do anything else.
E.g, it prints the *target* tripe, not the build triple.
> but I am wondering if
> it shouldn't be OK for building on a FreeBSD host
>
> .if ${TARGET_ARCH:Marmv6*} && (!defined(CPUTYPE) || ${CPUTYPE:M*soft*} == "")
> TARGET_ABI= -gnueabihf
> .elif ${TARGET_ARCH:Marm*}
> TARGET_ABI= -gnueabi
> .else
> TARGET_ABI=
> .endif
> VENDOR= unknown
> OS_VERSION= freebsd12.0
> +BUILD_OS!= uname -s
> +
Again, this should be set by the top-level Makefiles, not in this one.
>
> TARGET_TRIPLE?=
> ${TARGET_ARCH:C/amd64/x86_64/:C/arm64/aarch64/}-${VENDOR}-${OS_VERSION}${TARGET_ABI}
> +.if ${BUILD_OS} == FreeBSD
> BUILD_TRIPLE?=
> ${BUILD_ARCH:C/amd64/x86_64/:C/arm64/aarch64/}-${VENDOR}-${OS_VERSION}
> +.else
> +HOST_CC_DUMPMACHINE!= cc -dumpmachine
> +BUILD_TRIPLE?= ${HOST_CC_DUMPMACHINE}
> +.endif
>
> What do you think, should the code be instead:
>
> .if ${TARGET_ARCH:Marmv6*} && (!defined(CPUTYPE) || ${CPUTYPE:M*soft*} == "")
> TARGET_ABI= -gnueabihf
> .elif ${TARGET_ARCH:Marm*}
> TARGET_ABI= -gnueabi
> .else
> TARGET_ABI=
> .endif
> VENDOR= unknown
> OS_VERSION= freebsd12.0
>
> TARGET_TRIPLE?=
> ${TARGET_ARCH:C/amd64/x86_64/:C/arm64/aarch64/}-${VENDOR}-${OS_VERSION}${TARGET_ABI}
> +HOST_CC_DUMPMACHINE!= cc -dumpmachine
> +BUILD_TRIPLE?= ${HOST_CC_DUMPMACHINE}
No, this is definitely incorrect, as stated above.
-Dimitry
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