[Buildroot] [PATCH v2 1/1] qemu: add support for python3

[Baruch Siach <baruch@tkos.co.il>]

Hi Adam,

Adam Duskett writes:
> How would I test this? I am used to having BuildRoot handle the paths
> for such dependencies.

Just send RFC patch that you tested on your host with whatever Python
version you have installed. There are a number of participants in this
list that have access to hosts running RHEL6 or its derivatives.

With host installed Python being used there might be no need to
explicitly set the path of the Python executable, isn't it?

baruch

> On Tue, Sep 4, 2018 at 11:59 PM Baruch Siach <baruch@tkos.co.il> wrote:
>> Hi Adam,
>>
>> On Tue, Sep 04, 2018 at 03:09:26PM -0400, Adam Duskett wrote:
>> > I'm not sure;
>> >
>> > We support Distributions as old as CentOS6, which have very very old
>> > versions of Python...
>>
>> Buildroot requires Python version 2.6 or newer:
>>
>>   https://buildroot.org/downloads/manual/manual.html#requirement-mandatory
>>
>> Can Python 2.6 build qemu?
>>
>> baruch
>>
>> > On Tue, Sep 4, 2018 at 2:47 PM Baruch Siach <baruch@tkos.co.il> wrote:
>> > > Adam Duskett writes:
>> > > > qemu 2.12.0 now supports building against python3.
>> > > > see: https://wiki.qemu.org/ChangeLog/2.12#Build_Dependencies
>> > > >
>> > > > Signed-off-by: Adam Duskett <aduskett@gmail.com>
>> > > > ---
>> > > > Changes v1 -> v2:
>> > > >   - Split the python version check into two seperate checks for
>> > > >     readability, one for the target, one for the host.
>> > > >   - Fix location of the python version check for target and host.
>> > > >
>> > > >  package/qemu/qemu.mk | 27 ++++++++++++++++++++++-----
>> > > >  1 file changed, 22 insertions(+), 5 deletions(-)
>> > > >
>> > > > diff --git a/package/qemu/qemu.mk b/package/qemu/qemu.mk
>> > > > index afb2aa92f6..6dd9ce4a62 100644
>> > > > --- a/package/qemu/qemu.mk
>> > > > +++ b/package/qemu/qemu.mk
>> > > > @@ -16,7 +16,7 @@ QEMU_LICENSE_FILES = COPYING COPYING.LIB
>> > > >  #-------------------------------------------------------------
>> > > >  # Target-qemu
>> > > >
>> > > > -QEMU_DEPENDENCIES = host-pkgconf host-python libglib2 zlib pixman
>> > > > +QEMU_DEPENDENCIES = host-pkgconf libglib2 zlib pixman
>> > > >
>> > > >  # Need the LIBS variable because librt and libm are
>> > > >  # not automatically pulled. :-(
>> > > > @@ -25,9 +25,19 @@ QEMU_LIBS = -lrt -lm
>> > > >  QEMU_OPTS =
>> > > >
>> > > >  QEMU_VARS = \
>> > > > -     LIBTOOL=$(HOST_DIR)/bin/libtool \
>> > > > -     PYTHON=$(HOST_DIR)/bin/python2 \
>> > > > +     LIBTOOL=$(HOST_DIR)/bin/libtool
>> > > > +
>> > > > +ifeq ($(BR2_PACKAGE_PYTHON3),y)
>> > > > +QEMU_DEPENDENCIES += host-python3
>> > > > +QEMU_VARS += \
>> > > > +     PYTHON=$(HOST_DIR)/bin/python3 \
>> > > > +     PYTHONPATH=$(TARGET_DIR)/usr/lib/python$(PYTHON3_VERSION_MAJOR)/site-packages
>> > > > +else
>> > > > +QEMU_DEPENDENCIES += host-python
>> > > > +QEMU_VARS += \
>> > > > +     PYTHON=$(HOST_DIR)/bin/python \
>> > > >       PYTHONPATH=$(TARGET_DIR)/usr/lib/python$(PYTHON_VERSION_MAJOR)/site-packages
>> > > > +endif
>> > >
>> > > Can't we use the host installed python? Python is already a dependency
>> > > of Buildroot.
>> > >
>> > > baruch
>> > >
>> > > >  # If we want to specify only a subset of targets, we must still enable all
>> > > >  # of them, so that QEMU properly builds its list of default targets, from
>> > > > @@ -150,7 +160,7 @@ $(eval $(generic-package))
>> > > >  #-------------------------------------------------------------
>> > > >  # Host-qemu
>> > > >
>> > > > -HOST_QEMU_DEPENDENCIES = host-pkgconf host-python host-zlib host-libglib2 host-pixman
>> > > > +HOST_QEMU_DEPENDENCIES = host-pkgconf host-zlib host-libglib2 host-pixman
>> > > >
>> > > >  #       BR ARCH         qemu
>> > > >  #       -------         ----
>> > > > @@ -263,12 +273,19 @@ define HOST_QEMU_CONFIGURE_CMDS
>> > > >               --interp-prefix=$(STAGING_DIR) \
>> > > >               --cc="$(HOSTCC)" \
>> > > >               --host-cc="$(HOSTCC)" \
>> > > > -             --python=$(HOST_DIR)/bin/python2 \
>> > > >               --extra-cflags="$(HOST_CFLAGS)" \
>> > > >               --extra-ldflags="$(HOST_LDFLAGS)" \
>> > > >               $(HOST_QEMU_OPTS)
>> > > >  endef
>> > > >
>> > > > +ifeq ($(BR2_PACKAGE_PYTHON3),y)
>> > > > +HOST_QEMU_DEPENDENCIES += host-python3
>> > > > +HOST_QEMU_CONFIGURE_CMDS += --python=$(HOST_DIR)/bin/python3
>> > > > +else
>> > > > +HOST_QEMU_DEPENDENCIES += host-python
>> > > > +HOST_QEMU_CONFIGURE_CMDS += --python=$(HOST_DIR)/bin/python2
>> > > > +endif
>> > > > +
>> > > >  define HOST_QEMU_BUILD_CMDS
>> > > >       $(HOST_MAKE_ENV) $(MAKE) -C $(@D)
>> > > >  endef

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