On Tue, Aug 20, 2013 at 01:23:18PM -0600, Eric Blake wrote:
> On 08/20/2013 08:39 AM, Guido Günther wrote:
> > by adding it to AM_LDFLAGS instead of every linking rule and
> > by avoiding a forked grep.
> > ---
> > Daniel kind of nacked the AM_LDFLAGS part already but I think it's a
> > reasonable cleanup. We should rather use AM_LDFLAGS everywhere which
> > (we currently don't and which would be another cleanup). Or are there
> > any reasons to not have a read only GOT?
>
> Personally, I like the idea of using AM_LDFLAGS everywhere, but as
> Daniel and I have opposing opinions, we'll need a third person to speak up.
O.k. I think we lose more by not having eqaul AM_LDFLAGS everywhere
since there are already several places that did lack some flags since
it's error prone to maintain all locations correctly.
>
> > +++ b/m4/virt-linker-relro.m4
> > @@ -22,10 +22,10 @@ AC_DEFUN([LIBVIRT_LINKER_RELRO],[
> > AC_MSG_CHECKING([for how to force completely read-only GOT table])
> >
> > RELRO_LDFLAGS=
> > - `$LD --help 2>&1 | grep -- "-z relro" >/dev/null` && \
> > - RELRO_LDFLAGS="-Wl,-z -Wl,relro"
> > - `$LD --help 2>&1 | grep -- "-z now" >/dev/null` && \
> > - RELRO_LDFLAGS="$RELRO_LDFLAGS -Wl,-z -Wl,now"
> > + case `$LD --help 2>&1` in
> > + *"-z relro"*) RELRO_LDFLAGS="-Wl,-z -Wl,relro" ;&
>
> ';&' is a bashism; it is not portable to configure scripts
>
> > + *"-z now"*) RELRO_LDFLAGS="$RELRO_LDFLAGS -Wl,-z -Wl,now" ;;
> > + esac
>
> Instead, this needs to be:
>
> ld_help=`$LD --help 2>&1`
> case $ld_help in
> *"-z relro"*) RELRO_LDFLAGS="-Wl,-z -Wl,relro" ;;
> esac
> case $ld_help in
> *"-z now"*) RELRO_LDFLAGS="$RELRO_LDFLAGS -Wl,-z -Wl,now" ;;
> esac
>
>
> > @@ -1812,7 +1814,6 @@ libvirt_la_LDFLAGS = \
> > -version-info $(LIBVIRT_VERSION_INFO) \
> > $(LIBVIRT_NODELETE) \
> > $(AM_LDFLAGS) \
> > - $(RELRO_LDFLAGS) \
> > $(CYGWIN_EXTRA_LDFLAGS) \
> > $(MINGW_EXTRA_LDFLAGS) \
> > $(NULL)
>
> Hmm - maybe I see why Daniel expressed his opinion for not using
> $(AM_LDFLAGS) - notice that libraries to NOT use $(PIE_LDFLAGS)...
>
> > @@ -1964,7 +1963,6 @@ virtlockd_CFLAGS = \
> > virtlockd_LDFLAGS = \
> > $(AM_LDFLAGS) \
> > $(PIE_LDFLAGS) \
> > - $(RELRO_LDFLAGS) \
> > $(CYGWIN_EXTRA_LDFLAGS) \
> > $(MINGW_EXTRA_LDFLAGS) \
> > $(NULL)
>
> ...but executables do. But even then, maybe we want:
>
> LIBRARY_LDFLAGS = $(AM_LDFLAGS)
> EXEC_LDFLAGS = $(AM_LDFLAGS) $(PIE_LDFLAGS)
That would be fine with me but I'd do this as a separate cleanup since
AM_LDFLAGS currently only carries flags suitable for both lib and
executable builds.
Cheers,
-- Guido
> then use the appropriate $({LIBRARY,EXEC}_LDFLAGS) in each place, rather
> than having lots of duplicate $(PIE_LDFLAGS)?
>
> --
> Eric Blake eblake redhat com +1-919-301-3266
> Libvirt virtualization library http://libvirt.org
>
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