[Qemu-devel] [PATCH] rules.mak: Also try -r to build modules

[Qemu-devel] [PATCH] rules.mak: Also try -r to build modules

[Paolo Bonzini]

Building qemu fails in distributions where gcc enables PIE by default
(e.g. Debian unstable) with:

/usr/bin/ld: -r and -pie may not be used together

You have to use -r instead of -Wl,-r to avoid gcc passing -pie to the linker
when PIE is enabled and a relocatable object is passed.  However, clang
does not know about -r, so try -Wl,-r first.

Reported-by: Adrian Bunk <bunk@stusta.de>
Cc: qemu-stable@nongnu.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 configure | 10 ++++++++--
 rules.mak |  2 +-
 2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/configure b/configure
index 5e66828..c2508fe 100755
--- a/configure
+++ b/configure
@@ -4723,8 +4723,14 @@ EOF
 if ! compile_object ""; then
   error_exit "Failed to compile object file for LD_REL_FLAGS test"
 fi
-if do_cc -nostdlib -Wl,-r -Wl,--no-relax -o $TMPMO $TMPO; then
-  LD_REL_FLAGS="-Wl,--no-relax"
+for i in '-Wl,-r -Wl,--no-relax' -Wl,-r -r; do
+  if do_cc -nostdlib $i -o $TMPMO $TMPO; then
+    LD_REL_FLAGS=$i
+    break
+  fi
+done
+if test "$modules" = "yes" && test "$LD_REL_FLAGS" = ""; then
+  feature_not_found "modules" "Cannot find how to build relocatable objects"
 fi
 
 ##########################################
diff --git a/rules.mak b/rules.mak
index 0333ae3..f4839d2 100644
--- a/rules.mak
+++ b/rules.mak
@@ -93,7 +93,7 @@ module-common.o: CFLAGS += $(DSO_OBJ_CFLAGS)
 	$(if $(findstring /,$@),$(call quiet-command,cp $@ $(subst /,-,$@),"CP","$(subst /,-,$@)"))
 
 
-LD_REL := $(CC) -nostdlib -Wl,-r $(LD_REL_FLAGS)
+LD_REL := $(CC) -nostdlib $(LD_REL_FLAGS)
 
 %.mo:
 	$(call quiet-command,$(LD_REL) -o $@ $^,"LD","$(TARGET_DIR)$@")
-- 
2.9.3

Re: [Qemu-devel] [PATCH] rules.mak: Also try -r to build modules

[Stefan Hajnoczi]

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On Tue, Nov 29, 2016 at 04:37:20PM +0100, Paolo Bonzini wrote:
> Building qemu fails in distributions where gcc enables PIE by default
> (e.g. Debian unstable) with:
> 
> /usr/bin/ld: -r and -pie may not be used together
> 
> You have to use -r instead of -Wl,-r to avoid gcc passing -pie to the linker
> when PIE is enabled and a relocatable object is passed.  However, clang
> does not know about -r, so try -Wl,-r first.
> 
> Reported-by: Adrian Bunk <bunk@stusta.de>
> Cc: qemu-stable@nongnu.org
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  configure | 10 ++++++++--
>  rules.mak |  2 +-
>  2 files changed, 9 insertions(+), 3 deletions(-)

Thanks, applied to my staging tree:
https://github.com/stefanha/qemu/commits/staging

Stefan

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Re: [Qemu-devel] [PATCH] rules.mak: Also try -r to build modules

[Paolo Bonzini]

On 29/11/2016 17:22, Stefan Hajnoczi wrote:
> On Tue, Nov 29, 2016 at 04:37:20PM +0100, Paolo Bonzini wrote:
>> Building qemu fails in distributions where gcc enables PIE by default
>> (e.g. Debian unstable) with:
>>
>> /usr/bin/ld: -r and -pie may not be used together
>>
>> You have to use -r instead of -Wl,-r to avoid gcc passing -pie to the linker
>> when PIE is enabled and a relocatable object is passed.  However, clang
>> does not know about -r, so try -Wl,-r first.
>>
>> Reported-by: Adrian Bunk <bunk@stusta.de>
>> Cc: qemu-stable@nongnu.org
>> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
>> ---
>>  configure | 10 ++++++++--
>>  rules.mak |  2 +-
>>  2 files changed, 9 insertions(+), 3 deletions(-)
> 
> Thanks, applied to my staging tree:
> https://github.com/stefanha/qemu/commits/staging

Okay, then I'll send my pull request without this one.

Paolo

Re: [Qemu-devel] [PATCH] rules.mak: Also try -r to build modules

[Stefan Hajnoczi]

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On Tue, Nov 29, 2016 at 05:57:04PM +0100, Paolo Bonzini wrote:
> 
> 
> On 29/11/2016 17:22, Stefan Hajnoczi wrote:
> > On Tue, Nov 29, 2016 at 04:37:20PM +0100, Paolo Bonzini wrote:
> >> Building qemu fails in distributions where gcc enables PIE by default
> >> (e.g. Debian unstable) with:
> >>
> >> /usr/bin/ld: -r and -pie may not be used together
> >>
> >> You have to use -r instead of -Wl,-r to avoid gcc passing -pie to the linker
> >> when PIE is enabled and a relocatable object is passed.  However, clang
> >> does not know about -r, so try -Wl,-r first.
> >>
> >> Reported-by: Adrian Bunk <bunk@stusta.de>
> >> Cc: qemu-stable@nongnu.org
> >> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> >> ---
> >>  configure | 10 ++++++++--
> >>  rules.mak |  2 +-
> >>  2 files changed, 9 insertions(+), 3 deletions(-)
> > 
> > Thanks, applied to my staging tree:
> > https://github.com/stefanha/qemu/commits/staging
> 
> Okay, then I'll send my pull request without this one.

FWIW I applied the pull request with the broken -r fix.  Then I applied
this patch on top (and added a note to the commit description explaining
this was a refinement).  I've also merged your newest pull request for
-rc2.

Hopefully this got us into a more or less the state you expected? :)

Stefan

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Re: [Qemu-devel] [PATCH] rules.mak: Also try -r to build modules

[Paolo Bonzini]

On 29/11/2016 18:16, Stefan Hajnoczi wrote:
> FWIW I applied the pull request with the broken -r fix.  Then I applied
> this patch on top (and added a note to the commit description explaining
> this was a refinement).  I've also merged your newest pull request for
> -rc2.

Ok, that pull request (as expected) is a no-op if you kept v1 in the
tree.  I thought you hadn't because you didn't mention fixing the
mini-conflict here.

Paolo