Re: [SECOND RESEND] [PATCH] tools/python: Pass linker to Python build process

["Marek Marczykowski-Górecki" <marmarek@invisiblethingslab.com>]

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On Tue, Oct 13, 2020 at 01:26:06PM +0000, Wei Liu wrote:
> On Sun, Oct 11, 2020 at 06:11:39PM -0700, Elliott Mitchell wrote:
> > Unexpectedly the environment variable which needs to be passed is
> > $LDSHARED and not $LD.  Otherwise Python may find the build `ld` instead
> > of the host `ld`.
> > 
> > Replace $(LDFLAGS) with $(SHLIB_LDFLAGS) as Python needs shared objects
> > it can load at runtime, not executables.
> > 
> > This uses $(CC) instead of $(LD) since Python distutils appends $CFLAGS
> > to $LDFLAGS which breaks many linkers.
> > 
> > Signed-off-by: Elliott Mitchell <ehem+xen@m5p.com>
> > ---
> > This is now the *third* time this has been sent to the list.  Mark Pryor
> > has tested and confirms Python cross-building is working.  There is one
> > wart left which I'm unsure of the best approach for.
> > 
> > Having looked around a bit, I believe this is a Python 2/3 compatibility
> > issue.  "distutils" for Python 2 likely lacked a separate $LDSHARED or
> > $LD variable, whereas Python 3 does have this.  Alas this is pointless
> > due to the above (unless you can cause distutils.py to do the final link
> > step separately).
> 
> I think this is well-reasoned but I don't have time to figure out and
> verify the details.

Yes, it looks like distutils in Python 2 was even more limited than
the one in Python 3.

> Marek, do you have any comment on this?
> 
> > ---
> >  tools/pygrub/Makefile | 9 +++++----
> >  tools/python/Makefile | 9 +++++----
> >  2 files changed, 10 insertions(+), 8 deletions(-)
> > 
> > diff --git a/tools/pygrub/Makefile b/tools/pygrub/Makefile
> > index 3063c4998f..37b2146214 100644
> > --- a/tools/pygrub/Makefile
> > +++ b/tools/pygrub/Makefile
> > @@ -3,20 +3,21 @@ XEN_ROOT = $(CURDIR)/../..
> >  include $(XEN_ROOT)/tools/Rules.mk
> >  
> >  PY_CFLAGS = $(CFLAGS) $(PY_NOOPT_CFLAGS)
> > -PY_LDFLAGS = $(LDFLAGS) $(APPEND_LDFLAGS)
> > +PY_LDFLAGS = $(SHLIB_LDFLAGS) $(APPEND_LDFLAGS)
> >  INSTALL_LOG = build/installed_files.txt
> >  
> >  .PHONY: all
> >  all: build
> >  .PHONY: build
> >  build:
> > -	CC="$(CC)" CFLAGS="$(PY_CFLAGS)" LDFLAGS="$(PY_LDFLAGS)" $(PYTHON) setup.py build
> > +	CC="$(CC)" CFLAGS="$(PY_CFLAGS)" LDSHARED="$(CC)" LDFLAGS="$(PY_LDFLAGS)" $(PYTHON) setup.py build
> >  
> >  .PHONY: install
> >  install: all
> >  	$(INSTALL_DIR) $(DESTDIR)/$(bindir)
> > -	CC="$(CC)" CFLAGS="$(PY_CFLAGS)" LDFLAGS="$(PY_LDFLAGS)" $(PYTHON) \
> > -		setup.py install --record $(INSTALL_LOG) $(PYTHON_PREFIX_ARG) \
> > +	CC="$(CC)" CFLAGS="$(PY_CFLAGS)" LDSHARED="$(CC)" \
> > +		LDFLAGS="$(PY_LDFLAGS)" $(PYTHON) setup.py install \
> > +		--record $(INSTALL_LOG) $(PYTHON_PREFIX_ARG) \
> >  		 --root="$(DESTDIR)" --install-scripts=$(LIBEXEC_BIN) --force
> >  	set -e; if [ $(bindir) != $(LIBEXEC_BIN) -a \
> >  	             "`readlink -f $(DESTDIR)/$(bindir)`" != \
> > diff --git a/tools/python/Makefile b/tools/python/Makefile
> > index 8d22c03676..b675f5b4de 100644
> > --- a/tools/python/Makefile
> > +++ b/tools/python/Makefile
> > @@ -5,19 +5,20 @@ include $(XEN_ROOT)/tools/Rules.mk
> >  all: build
> >  
> >  PY_CFLAGS = $(CFLAGS) $(PY_NOOPT_CFLAGS)
> > -PY_LDFLAGS = $(LDFLAGS) $(APPEND_LDFLAGS)
> > +PY_LDFLAGS = $(SHLIB_LDFLAGS) $(APPEND_LDFLAGS)
> >  INSTALL_LOG = build/installed_files.txt
> >  
> >  .PHONY: build
> >  build:
> > -	CC="$(CC)" CFLAGS="$(PY_CFLAGS)" $(PYTHON) setup.py build
> > +	CC="$(CC)" CFLAGS="$(PY_CFLAGS)" LDSHARED="$(CC)" LDFLAGS="$(PY_LDFLAGS)" $(PYTHON) setup.py build
> >  
> >  .PHONY: install
> >  install:
> >  	$(INSTALL_DIR) $(DESTDIR)$(LIBEXEC_BIN)
> >  
> > -	CC="$(CC)" CFLAGS="$(PY_CFLAGS)" LDFLAGS="$(PY_LDFLAGS)" $(PYTHON) \
> > -		setup.py install --record $(INSTALL_LOG) $(PYTHON_PREFIX_ARG) \
> > +	CC="$(CC)" CFLAGS="$(PY_CFLAGS)" LDSHARED="$(CC)" \
> > +		LDFLAGS="$(PY_LDFLAGS)" $(PYTHON) setup.py install \
> > +		--record $(INSTALL_LOG) $(PYTHON_PREFIX_ARG) \
> >  		--root="$(DESTDIR)" --force
> >  
> >  	$(INSTALL_PYTHON_PROG) scripts/convert-legacy-stream $(DESTDIR)$(LIBEXEC_BIN)
> > -- 
> > 2.20.1
> > 
> > 
> > -- 
> > (\___(\___(\______          --=> 8-) EHM <=--          ______/)___/)___/)
> >  \BS (    |         ehem+sigmsg@m5p.com  PGP 87145445         |    )   /
> >   \_CS\   |  _____  -O #include <stddisclaimer.h> O-   _____  |   /  _/
> > 8A19\___\_|_/58D2 7E3D DDF4 7BA6 <-PGP-> 41D1 B375 37D0 8714\_|_/___/5445
> > 
> > 

-- 
Best Regards,
Marek Marczykowski-Górecki
Invisible Things Lab
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?

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