[ipxe-devel] [PATCH 1/1] [build] Fix no-PIE workaround for i386 builds

[Christian Hesse]

Michael Brown <mcb30 at ipxe.org> on Fri, 2015/04/24 17:41:
> On 08/04/15 09:13, Christian Hesse wrote:
> > diff --git a/src/arch/i386/Makefile b/src/arch/i386/Makefile
> > index 99f8753..897081b 100644
> > --- a/src/arch/i386/Makefile
> > +++ b/src/arch/i386/Makefile
> > @@ -75,8 +75,8 @@ CFLAGS			+= -Ui386
> >   # 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')
> > +PIE_TEST = $(CC) -dM -E - < /dev/null | grep -q '__PIE__'
> > +PIE_FLAGS := $(shell $(PIE_TEST) && $(ECHO) '-fno-PIE')
> >   WORKAROUND_CFLAGS += $(PIE_FLAGS)
> >   endif
> 
> The original fix (in http://git.ipxe.org/ipxe.git/commitdiff/fe61f6d) 
> added both -fno-PIE and -nopie if it detected that the workaround was 
> necessary: the -fno-PIE is for compilation and the -nopie is to instruct 
> gcc to not pass "-pie" to the linker (i.e. not to default to -Wl,-pie).
> 
> Since we (I think) always invoke the linker directly via $(LD), it's 
> plausible that the -nopie was never needed.  Is this the case?  (I don't 
> have any systems on which the workaround is necessary, so can't test 
> this for myself.)

The problem is that gcc does not know the command option -nopie here:

% gcc -fno-PIE -nopie -x c -c /dev/null -o /dev/null
gcc: error: unrecognized command line option ‘-nopie’
% echo $?
1

So the check always fails and the workaround is never applied.
(I missed to update the comment, though...)
-- 
main(a){char*c=/*    Schoene Gruesse                         */"B?IJj;MEH"
"CX:;",b;for(a/*    Chris           get my mail address:    */=0;b=c[a++];)
putchar(b-1/(/*               gcc -o sig sig.c && ./sig    */b/42*2-3)*42);}
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