Syslinux - Dec 2011 - [PATCH] Fix compilation when gcc is patched to default to -fPIE -Wl, -pie

gcc hardened by default is seen on gentoo, alt-linux, HLFS, etc.

Patch fix on syslinux this error during gpxe compilation:
  [BUILD] bin/cpu.o
arch/i386/core/cpu.c: In function 'get_cpuinfo':
arch/i386/include/bits/cpu.h:79: error: can't find a register in class
'BREG' while reloading 'asm'
arch/i386/include/bits/cpu.h:79: error: can't find a register in class
'BREG' while reloading 'asm'
arch/i386/include/bits/cpu.h:79: error: can't find a register in class
'BREG' while reloading 'asm'
arch/i386/include/bits/cpu.h:79: error: can't find a register in class
'BREG' while reloading 'asm'
arch/i386/include/bits/cpu.h:79: error: 'asm' operand has impossible
constraints
arch/i386/include/bits/cpu.h:79: error: 'asm' operand has impossible
constraints
arch/i386/include/bits/cpu.h:79: error: 'asm' operand has impossible
constraints
arch/i386/include/bits/cpu.h:79: error: 'asm' operand has impossible
constraints
make[3]: *** [bin/cpu.o] Error 1

Mostly same fix has been applied on ipxe tree, the only change is on the
variable name to hold the flags.
Compile tested against 4.05-pre7

Signed-off-by: Gilles Espinasse <g.esp at free.fr>
---
 gpxe/src/Makefile.housekeeping |   11 +++++++++++
 1 files changed, 11 insertions(+), 0 deletions(-)

diff --git a/gpxe/src/Makefile.housekeeping b/gpxe/src/Makefile.housekeeping
index 1f5e115..d351a52 100644
--- a/gpxe/src/Makefile.housekeeping
+++ b/gpxe/src/Makefile.housekeeping
@@ -134,6 +134,17 @@ SP_FLAGS := $(shell $(SP_TEST) && $(ECHO)
'-fno-stack-protector')
 CFLAGS	+= $(SP_FLAGS)
 endif
 
+# Some widespread patched versions of gcc include -fPIE -Wl,-pie by
+# default.  Note that gcc will exit *successfully* if it fails to
+# recognise an option that starts with "no", so we have to test for
+# output on stderr instead of checking the exit status.
+#
+ifeq ($(CCTYPE),gcc)
+PIE_TEST = [ -z "`$(CC) -fno-PIE -nopie -x c -c /dev/null -o /dev/null
2>&1`" ]
+PIE_FLAGS := $(shell $(PIE_TEST) && $(ECHO) '-fno-PIE -nopie')
+CFLAGS += $(PIE_FLAGS)
+endif
+
 # gcc 4.4 generates .eh_frame sections by default, which distort the
 # output of "size".  Inhibit this.
 #
-- 
1.5.6.5

On 12/09/2011 04:11 AM, Gilles Espinasse wrote:
>  
> +# Some widespread patched versions of gcc include -fPIE -Wl,-pie by
> +# default.  Note that gcc will exit *successfully* if it fails to
> +# recognise an option that starts with "no", so we have to test
for
> +# output on stderr instead of checking the exit status.
> +#
> +ifeq ($(CCTYPE),gcc)
> +PIE_TEST = [ -z "`$(CC) -fno-PIE -nopie -x c -c /dev/null -o
/dev/null 2>&1`" ]
> +PIE_FLAGS := $(shell $(PIE_TEST) && $(ECHO) '-fno-PIE
-nopie')
> +CFLAGS += $(PIE_FLAGS)
> +endif
> +
If gcc will exit successfully, then isn't that good enough?

	-hpa