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From: Jonathan Wakely <jwakely.gcc@gmail.com>
To: Xi Ruoyao <xry111@mengyan1223.wang>
Cc: Thomas Sobczynski <tsobczynski@werfen.com>,
	"gcc-help@gcc.gnu.org" <gcc-help@gcc.gnu.org>
Subject: Re: [EXTERNAL] Re: Compiling GCC 11 for Windows targeting ARM on Linux
Date: Tue, 11 Jan 2022 11:19:03 +0000	[thread overview]
Message-ID: <CAH6eHdS_rY0xU8k4UMuYAgQEzQX5+3YX3qg8okSNJ9rObxv3LQ@mail.gmail.com> (raw)
In-Reply-To: <ccae4285330b641307b9f25de93d4bad4fa4df10.camel@mengyan1223.wang>

On Tue, 11 Jan 2022 at 06:54, Xi Ruoyao wrote:
>
> On Tue, 2022-01-11 at 03:44 +0000, Thomas Sobczynski wrote:
> > Update: I kept peering at the configure scripts and their embedded
> > comments, and concluded that it's at least worth trying to add "--
> > with-newlib" to the configure script parameters. That may not be the
> > right move, but it did get me further into the build process. However,
> > although its configure script finished, the GCC build seems unable to
> > compile libstdc++ (tail end of output below).
> >
> > Am I barking up the wrong tree with "--with-newlib"?
>
> I think --with-newlib is needed, as it's the de-facto C library on bare
> metal ARM.  But you need to install newlib for the target before
> building libstdc++, because libstdc++ needs a C library.

Strictly speaking it doesn't need one, but you have to use
--disable-hosted-libstdcxx --without-headers --with-newlib to tell it
you have no C library.

On the master branch you no longer need the --with-newlib for that
case (PR 103866). Building trunk, or backporting the fix for that bug
to gcc-11, might make life easier.



>
> And your configuration may trigger
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100017, which is fixed in
> GCC 11 branch recently.  You may need to "git pull" your GCC 11 branch
> to overcome it.

Yes, building a canadian cross for bare metal, involving Windows, is
like falling out of the ugly tree and hitting every branch on the way
down.

> Maybe you can add --disable-libstdcxx and build a GCC without libstdc++,
> reboot into Windows, and then compile newlib & libstdc++ for target with
> the toolchain just built.
>
> However, honestly I don't do any serious development on Windows...

> > Does it make sense that the build is supplying include search
> > directories from the GCC v11 build tree (compiler being compiled) to
> > the native cross compiler which is GCC v9.x? I already misunderstood
> > the build/host/target config earlier. Is it perhaps not_a_ GCC cross
> > toolchain that I need, but perhaps I need to build _the_ compiler
> > (v11) and then turn around and use it to build for the non-native
> > Host?
>
> "__has_builtin" is introduced in GCC 10, so GCC 9 can't recognize it.
> IIRC libstdc++ from a specific GCC version is only expected to be built
> with GCC with the same version.

Correct.

  reply	other threads:[~2022-01-11 11:19 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-01-10 16:47 Thomas Sobczynski
2022-01-10 17:16 ` Xi Ruoyao
2022-01-11  2:49   ` [EXTERNAL] " Thomas Sobczynski
2022-01-11  3:44     ` Thomas Sobczynski
2022-01-11  6:53       ` Xi Ruoyao
2022-01-11 11:19         ` Jonathan Wakely [this message]
2022-01-11 11:14       ` Jonathan Wakely
2022-01-12 18:39         ` Thomas Sobczynski
2022-01-12 19:09           ` Jonathan Wakely
2022-01-11 11:09     ` Jonathan Wakely
2022-01-10 17:24 ` Jonathan Wakely
2022-01-11  0:27   ` [EXTERNAL] " Thomas Sobczynski

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