Re: [Xen-devel] Build problems with xen 4.7

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Tue, May 31, 2016 at 07:27:24PM +0100, George Dunlap wrote:
> On Fri, May 13, 2016 at 4:23 PM, Konrad Rzeszutek Wilk
> <konrad.wilk@xxxxxxxxxx> wrote:
> > On Fri, May 13, 2016 at 03:25:52PM +0100, M A Young wrote:
> >> On Fri, 13 May 2016, Jan Beulich wrote:
> >>
> >> > >>> On 13.05.16 at 15:49, <konrad.wilk@xxxxxxxxxx> wrote:
> >> > > ...
> >> > >
> >> > > Still an issue - with 4.7.0-rc1.
> >> >
> >> > And I don't recall anyone having contributed a fix/workaround.
> >> >
> >> > > If I do:
> >> > >
> >> > > $export CFLAGS=" "'
> >> > > $make
> >> > >
> >> > > I end up with:
> >> > > gcc -E -O1 -fno-omit-frame-pointer -m64 -DBUILD_ID -g 
> >> > > -fno-strict-aliasing -std=gnu99
> >> > >[...]
> >> > > <command-line>:0:0: error: "__OBJECT_FILE__" redefined [-Werror]
> >> > > <command-line>:0:0: note: this is the location of the previous 
> >> > > definition
> >> > > <command-line>:0:0: error: "__OBJECT_LABEL__" redefined [-Werror]
> >> > > <command-line>:0:0: note: this is the location of the previous 
> >> > > definition
> >> > > cc1: all warnings being treated as errors
> >> > > Makefile:62: recipe for target 'compat/callback.i' failed
> >> >
> >> > My previous recommendation stands: Then just don't do this.
> >>
> >> I hacked around it for my test builds (eg. see my test build at
> >> https://copr.fedorainfracloud.org/coprs/myoung/xentest/build/204111/
> >> ) by not setting CFLAGS in the environment, but by instead adding the
> >> recommended Fedora RPM settings into config/StdGNU.mk via a different
> >> environment variable.
> >
> > ah:
> >
> > --- xen-4.7.0/config/StdGNU.mk.orig     2016-04-15 22:56:52.191227591 +0100
> > +++ xen-4.7.0/config/StdGNU.mk  2016-04-15 23:01:40.978829756 +0100
> > @@ -37,6 +37,12 @@
> >
> >  ifneq ($(debug),y)
> >  CFLAGS += -O2 -fomit-frame-pointer -fno-tree-coalesce-vars
> > +ifeq ($(XEN_TARGET_ARCH),x86_64)
> > +#might be cross-compiling so strip out possible x86_32 options
> > +CFLAGS += $(shell echo $(CFLAGS_EXTRA) | sed -e 's/-m32//g' -e 
> > 's/-march=i686//g' -e 's/-mtune=atom//g')
> > +else
> > +CFLAGS += $(CFLAGS_EXTRA)
> > +endif
> >  else
> >  # Less than -O1 produces bad code and large stack frames
> >  CFLAGS += -O1 -fno-omit-frame-pointer
> >
> >
> > And in the spec file:
> > export CFLAGS_EXTRA="$RPM_OPT_FLAGS"
> > make %{?_smp_mflags} %{?efi_flags} prefix=/usr dist-xen
> 
> Something like the above solution worked for me (CentOS 7 -- I'm
> suspecting a similar pattern here).
> 
> Adding CFLAGS="${RPM_OPT_FLAGS}" to my ./configure line made some
> noises as though it was going to work, but none of it actually ended
> up passed to the compiler (whereas it did with the little patch Konrad
> posted).
> 
> Are we going to provide a proper way for distros to add flags like
> this without having to hack the build system?

I like the suggestion he had for config/StdGNU.mk ..
> 
>  -George

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