Re: [PATCH] Update configure.ac so that we don't need glibc when running ./configure.

[Flavio Cruz]

For x86_64-pc-gnu we still do not have a working glibc so ./configure will fail
under a freestanding environment. We force ./configure to avoid running
compiled C programs as a test which it is not needed when compiling a kernel.
---
On Mon, Jan 09, 2023 at 07:52:21PM +0100, Samuel Thibault wrote:
> Flavio Cruz, le dim. 08 janv. 2023 21:49:40 -0500, a ecrit:
> > For x86_64-pc-gnu we still do not have a working glibc so ./configure will fail
> > under a freestanding environment. We force ./configure to avoid running
> > compiled C programs as a test which it is not needed when compiling a kernel.
> > ---
> >  configure.ac | 8 ++++++++
> >  1 file changed, 8 insertions(+)
> >
> > diff --git a/configure.ac b/configure.ac
> > index 3aaa935c..06a243a2 100644
> > --- a/configure.ac
> > +++ b/configure.ac
> > @@ -21,6 +21,9 @@ AC_INIT([AC_PACKAGE_NAME], [AC_PACKAGE_VERSION], 
> > [AC_PACKAGE_BUGREPORT],
> >    [AC_PACKAGE_TARNAME])
> >  AC_CONFIG_SRCDIR([kern/ipc_kobject.c])
> >
> > +# We don't need glibc to compile gnumach.
> > +: ${CFLAGS="-ffreestanding -nostdlib"}
>
> AIUI we can then drop these from Makefile.am?
> (better not duplicate flags, that most often leads to cargo cult).

Yes, here's the revised patch.

> >  AC_CONFIG_AUX_DIR([build-aux])
> >
> >  AM_INIT_AUTOMAKE(
> > @@ -79,7 +82,12 @@ AC_SUBST([systype])
> >  #
> >
> >  AC_PROG_AWK
> > +# Temporarily force cross compiling mode to make sure the configure script
> > +# does not try to run compiled binaries.
> > +save_cross_compiling=$cross_compiling
> > +cross_compiling=yes
> >  AM_PROG_AS
> > +cross_compiling=$save_cross_compiling
> >  AC_PROG_CC
> >  AC_PROG_CPP
> >  AC_PROG_INSTALL
> > --
> > 2.39.0

 Makefile.am  | 2 +-
 configure.ac | 8 ++++++++
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/Makefile.am b/Makefile.am
index 7b7247c5..1bcf7941 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -43,7 +43,7 @@ AM_LDFLAGS =
 
 GCC_INSTALL = $(shell LANG=C gcc -print-search-dirs | sed -n -e 's/install: \(.*\)/\1/p')
 AM_CPPFLAGS += \
-       -ffreestanding -nostdinc -imacros config.h -I $(GCC_INSTALL)/include
+       -imacros config.h -I $(GCC_INSTALL)/include
 
 AM_CPPFLAGS += \
        -I$(systype) \
diff --git a/configure.ac b/configure.ac
index 3aaa935c..8f10b5d5 100644
--- a/configure.ac
+++ b/configure.ac
@@ -21,6 +21,9 @@ AC_INIT([AC_PACKAGE_NAME], [AC_PACKAGE_VERSION], 
[AC_PACKAGE_BUGREPORT],
   [AC_PACKAGE_TARNAME])
 AC_CONFIG_SRCDIR([kern/ipc_kobject.c])
 
+# We don't need glibc to compile gnumach.
+CFLAGS="$CFLAGS -ffreestanding -nostdlib"
+
 AC_CONFIG_AUX_DIR([build-aux])
 
 AM_INIT_AUTOMAKE(
@@ -79,7 +82,12 @@ AC_SUBST([systype])
 #
 
 AC_PROG_AWK
+# Temporarily force cross compiling mode to make sure the configure script
+# does not try to run compiled binaries.
+save_cross_compiling=$cross_compiling
+cross_compiling=yes
 AM_PROG_AS
+cross_compiling=$save_cross_compiling
 AC_PROG_CC
 AC_PROG_CPP
 AC_PROG_INSTALL
--
2.39.0