Xen devel - Mar 2012 - [PATCH] qemu/configure: fix CFLAGS handling for i386

configure will generate incorrect CFLAGS which will lead to compile
errors due to unknown gcc options, IFF CFLAGS was already in the
environment during configure invocation.

Add a space before the -march=i486 gcc option.

This patch is against the qemu-xen tree, but it should apply also to
qemu.git since it has the same issue. Please apply to both trees.

Signed-off-by: Olaf Hering <olaf@aepfle.de>

---
 configure |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Index: qemu-xen-dir-remote/configure
==================================================================---
qemu-xen-dir-remote.orig/configure
+++ qemu-xen-dir-remote/configure
@@ -2637,7 +2637,7 @@ int main(int argc, char **argv)
 }
 EOF
   if ! compile_prog "" "" ; then
-    CFLAGS+="-march=i486"
+    CFLAGS+=" -march=i486"
   fi
 fi

Hi Olaf,

Am 30.03.2012 17:24, schrieb Olaf Hering:
> 
> configure will generate incorrect CFLAGS which will lead to compile
> errors due to unknown gcc options, IFF CFLAGS was already in the
> environment during configure invocation.
> 
> Add a space before the -march=i486 gcc option.
> 
> This patch is against the qemu-xen tree, but it should apply also to
> qemu.git since it has the same issue. Please apply to both trees.
> 
> Signed-off-by: Olaf Hering <olaf@aepfle.de>
The patch applies fine to upstream QEMU (we should strip leading qemu/
from the commit message though).

This is the only usage of += outside Makefile fragments, so I wonder if
its use may have been by accident. Is it safe in a POSIX context?
Or should we better use CFLAGS="$CFLAGS -march=486"?
For QEMU_CFLAGS we use the pattern QEMU_CFLAGS="-options $QEMU_CFLAGS"
to allow overriding options.

Andreas
> 
> ---
>  configure |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> Index: qemu-xen-dir-remote/configure
> ==================================================================> ---
qemu-xen-dir-remote.orig/configure
> +++ qemu-xen-dir-remote/configure
> @@ -2637,7 +2637,7 @@ int main(int argc, char **argv)
>  }
>  EOF
>    if ! compile_prog "" "" ; then
> -    CFLAGS+="-march=i486"
> +    CFLAGS+=" -march=i486"
>    fi
>  fi
>  
-- 
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg, Germany
GF: Jeff Hawn, Jennifer Guild, Felix Imendörffer; HRB 16746 AG Nürnberg

On Sat, Mar 31, Andreas Färber wrote:
> This is the only usage of += outside Makefile fragments, so I wonder if
> its use may have been by accident. Is it safe in a POSIX context?
> Or should we better use CFLAGS="$CFLAGS -march=486"?
Now that I look at the shebang, configure is a sh script and += is most
likely a bash feature. So your suggestion for the assignment is correct.

Olaf

On 31 March 2012 16:41, Andreas Färber <afaerber@suse.de>
wrote:
> This is the only usage of += outside Makefile fragments, so I wonder if
> its use may have been by accident. Is it safe in a POSIX context?
> Or should we better use CFLAGS="$CFLAGS -march=486"?
> For QEMU_CFLAGS we use the pattern QEMU_CFLAGS="-options
$QEMU_CFLAGS"
> to allow overriding options.
For that matter, should this be setting QEMU_CFLAGS instead of
CFLAGS? I have to say I''m not entirely sure what the difference
is...

-- PMM

On Sat, Mar 31, Peter Maydell wrote:
> On 31 March 2012 16:41, Andreas Färber <afaerber@suse.de> wrote:
> > This is the only usage of += outside Makefile fragments, so I wonder
if
> > its use may have been by accident. Is it safe in a POSIX context?
> > Or should we better use CFLAGS="$CFLAGS -march=486"?
> > For QEMU_CFLAGS we use the pattern QEMU_CFLAGS="-options
$QEMU_CFLAGS"
> > to allow overriding options.
> 
> For that matter, should this be setting QEMU_CFLAGS instead of
> CFLAGS? I have to say I''m not entirely sure what the difference
> is...
I havent looked into qemu build internals, but there is most likely a
concept of HOST_TOOLS_CFLAGS and TARGET_CFLAGS in qemus Makefiles.

Olaf

Am 31.03.2012 18:46, schrieb Olaf Hering:
> On Sat, Mar 31, Andreas Färber wrote:
> 
>> This is the only usage of += outside Makefile fragments, so I wonder if
>> its use may have been by accident. Is it safe in a POSIX context?
>> Or should we better use CFLAGS="$CFLAGS -march=486"?
> 
> Now that I look at the shebang, configure is a sh script and += is most
> likely a bash feature. So your suggestion for the assignment is correct.
...apart from the missing i in i486, obviously. ;)

Andreas

-- 
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg, Germany
GF: Jeff Hawn, Jennifer Guild, Felix Imendörffer; HRB 16746 AG Nürnberg