Date: Tue, 21 Jun 2016 15:11:18 -0700 From: Mark Millard <markmi@dsl-only.net> To: Bryan Drewery <bdrewery@FreeBSD.org>, FreeBSD Current <freebsd-current@freebsd.org> Cc: freebsd-arm <freebsd-arm@freebsd.org>, FreeBSD PowerPC ML <freebsd-ppc@freebsd.org> Subject: RE: WITH_SYSTEM_COMPILER default on Message-ID: <39C98FFD-B0BB-4F25-A1D1-2447A2FDDFBD@dsl-only.net>
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Bryan Drewery bdrewery at FreeBSD.org wrote on Tue Jun 21 19:03:46 UTC =
2016 :
> This feature is where the bootstrap compiler in buildworld is not =
built
> if the one in /usr/bin/cc matches what would be built. It is very
> conservative and requires a complete match of major/minor version and
> the compiler revision (__FreeBSD_cc_version).
>=20
> The only complaint so far about this feature was that when we bumped =
the
> compiler revision, too much of clang would rebuild. That was =
addressed
> in r301277.
>=20
> I would like to enable this feature by default in head for 11.0.
>=20
> Unless there are any objections I will do so in a few days.
>=20
> --=20
> Regards,
> Bryan Drewery
I've only been using WITH_SYSTEM_COMPILER=3D for system-clang based =
builds with the host matching TARGET_ARCH ("self hosted").
For xtoolchain use (self-hosted or not) I've been using in my src.conf =
files for such contexts:=20
WITHOUT_CROSS_COMPILER=3D
WITHOUT_SYSTEM_COMPILER=3D
WITHOUT_BINUTILS_BOOTSTRAP=3D
WITHOUT_CLANG_BOOTSTRAP=3D
For cross builds (all being amd64 -> something else, such as armv6, =
powerpc64, or powerpc) based on using some build of the system clang =
3.8.0 I've been using:
WITH_CROSS_COMPILER=3D
WITHOUT_SYSTEM_COMPILER=3D
WITH_BINUTILS_BOOTSTRAP=3D
WITH_CLANG_BOOTSTRAP=3D
As I understand the history the paths for finding tools, headers, etc. =
built into the clang cross compiler were not necessarily the same as for =
the live the system compiler that has paths appropriate specifically to =
self-hosting. This helped avoid getting the wrong versions of files =
involved.
This was true despite the normal clang code generation being able to =
target other architectures.
As for self-hosted system-clang based builds I've been using:
#WITH_CROSS_COMPILER=3D
WITH_SYSTEM_COMPILER=3D
WITH_BINUTILS_BOOTSTRAP=3D
#WITH_CLANG_BOOTSTRAP=3D
(So in this case I've left some things implicit in operation.)
As stands I'll not notice the SYSTEM_COMPILER default's consequences =
because I'm always explicit about WITH vs. WITHOUT for SYSTM_COMPILER. =
If you want some sort of experiment(s), let me know.
But I only currently have an amd64 context and a rpi2 armv6 context. The =
dual-proessor, each dual-core powerpc64 was much faster at self-hosted =
xtoolchain builds compared to any self-hosted rpi2 build but I do not =
have access to the powerpc family for now. Self-hosted amd64 xtoolchain =
builds do not work yet for normal settings: duplicate declarations tend =
to stop the builds if one leaves on the warnings-as-errors status for =
buildkernel. (At least last that I tried such.)
=3D=3D=3D
Mark Millard
markmi at dsl-only.net
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