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Date:      Sat, 30 Jun 2018 10:04:51 -0700
From:      Mark Millard <marklmi@yahoo.com>
To:        John Baldwin <jhb@FreeBSD.org>
Cc:        Dimitry Andric <dim@FreeBSD.org>, Bryan Drewery <bdrewery@FreeBSD.org>, svn-src-head@freebsd.org, FreeBSD Current <freebsd-current@freebsd.org>
Subject:   Re: head -r335782 (?) broke ci.freebsd.org's FreeBSD-head-amd64-gcc build (lib32 part of build)
Message-ID:  <49BF6569-96A9-4104-BDE6-8BB94C0D9626@yahoo.com>
In-Reply-To: <edcd2126-3554-f444-6ba0-3da94d887dfe@FreeBSD.org>
References:  <00D1127A-1F0E-4E0E-B86C-1C5AA5B2E085@yahoo.com> <CF0230A1-1384-4F0F-A96A-5AB555FD17AC@yahoo.com> <7A845F2C-C994-4828-823D-33A97B7B6EB0@yahoo.com> <72081b02-cf23-82ec-32df-7f5793c35f57@FreeBSD.org> <003509F0-F2F4-4A43-82FE-3F6FC23D19D4@yahoo.com> <65b19cc4-eaf0-13ed-43e6-9f04a1f7f196@FreeBSD.org> <FF369ACC-D496-49AF-BB41-406936E433B0@yahoo.com> <edcd2126-3554-f444-6ba0-3da94d887dfe@FreeBSD.org>

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On 2018-Jun-30, at 9:29 AM, John Baldwin <jhb at FreeBSD.org> wrote:

> On 6/30/18 9:17 AM, Mark Millard wrote:
>> On 2018-Jun-30, at 7:51 AM, John Baldwin <jhb at FreeBSD.org> wrote:
>>=20
>>> On 6/29/18 2:37 PM, Mark Millard wrote:
>>>> [I expect this is more than just amd64-gcc related but that is all
>>>> that ci.freebsd.org normally builds via a devel/*-gcc .]
>>>=20
>>> As indicated by my other mail, this is i386 and amd64 specific as it
>>> only matters for float.h on i386 due to the disagreement on
>>> LDBL_MANT_DIG.
>>=20
>> I was correct about the search order for include files being
>> different before -r335782 vs. -r335782 and later:
>=20
> Yes, but this is kind of a feature, not a bug, and the issue there is =
that
> as much as possible we should allow FreeBSD to work with the standard =
headers
> that are supposed to be part of the language (and thus provided by the
> toolchain).  Right now we don't ship any of the 'std*.h' headers clang
> provides for example in our base system clang, though a few months ago =
I
> fixed the one place that was using <machine/stdarg.h> instead of
> <stdarg.h> in userland that was breaking the use of the =
toolchain-provided
> stdarg.h (both GCC and clang).
>=20
>> Might this reversal have other effects even for
>> architectures for which the code does compile
>> via devel/*-gcc ?
>=20
> It depends on the header.  This particular failure is due to a quirk =
of
> <float.h> on FreeBSD/i386.  I have built other platforms with external
> GCC just fine.  To the extent that we encounter any other issues we
> should try to make our source more conformant with C and only fall =
back to
> axeing the toolchain-provided language headers as a last resort.

It is too bad that the review https://reviews.freebsd.org/D16055 did not
catch the change in what headers are used by buildworld and buildkernel.
I'd view such switching of long established header bindings as a
fairly big deal, possibly even warranting being explicitly proposed and
debated.

I'm not claiming my opinion on which search order that I have is
actually relevant. I'm just now nervous about my powerpc64-gcc based
builds having unexpected differences, for example. [I sometimes explore
the status of powerpc family builds via more modern toolchains.]

(But lib32 for powerpc64 via modern gcc's is messed up anyway,
generating code in crtbeginS.o for the wrong ABI: using R30 incorrectly.
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D206123 has more =
about
that.)

=3D=3D=3D
Mark Millard
marklmi at yahoo.com
( dsl-only.net went
away in early 2018-Mar)




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