| Message ID | 20200714033927.1516172-1-hancock@sedsystems.ca |
|---|---|
| State | Accepted |
| Headers | show |
| Series | package/scons: explicitly specify host Python 3 | expand |
On Mon, 13 Jul 2020 21:39:27 -0600 Robert Hancock <hancock@sedsystems.ca> wrote: > All packages using scons are now using Python 3 to run it, so > explicitly set scons as using host-python3. This avoids a > spurious host Python 2 dependency if BR2_PACKAGE_PYTHON3 is not > set (for example, if no Python is packaged for the target). > > Signed-off-by: Robert Hancock <hancock@sedsystems.ca> > --- > package/scons/scons.mk | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/package/scons/scons.mk b/package/scons/scons.mk > index da2ccceb08..a95fa7fd69 100644 > --- a/package/scons/scons.mk > +++ b/package/scons/scons.mk > @@ -10,6 +10,8 @@ SCONS_LICENSE = MIT > SCONS_LICENSE_FILES = LICENSE.txt > SCONS_SETUP_TYPE = distutils > > +HOST_SCONS_NEEDS_HOST_PYTHON = python3 I am just wondering if we should do our usual dance that consists in relying on python2 if enabled, i.e something like this: HOST_SCONS_NEEDS_HOST_PYTHON = $(if ($(BR2_PACKAGE_PYTHON),python,python3) or if we simply stop doing this and say that we switch to just python3. Titouan, what do you think ? Thomas
Hello Thomas, Robert and all, On 14/07/20 10:15, Thomas Petazzoni wrote: > On Mon, 13 Jul 2020 21:39:27 -0600 > Robert Hancock <hancock@sedsystems.ca> wrote: > >> All packages using scons are now using Python 3 to run it, so >> explicitly set scons as using host-python3. This avoids a >> spurious host Python 2 dependency if BR2_PACKAGE_PYTHON3 is not >> set (for example, if no Python is packaged for the target). >> >> Signed-off-by: Robert Hancock <hancock@sedsystems.ca> >> --- >> package/scons/scons.mk | 2 ++ >> 1 file changed, 2 insertions(+) >> >> diff --git a/package/scons/scons.mk b/package/scons/scons.mk >> index da2ccceb08..a95fa7fd69 100644 >> --- a/package/scons/scons.mk >> +++ b/package/scons/scons.mk >> @@ -10,6 +10,8 @@ SCONS_LICENSE = MIT >> SCONS_LICENSE_FILES = LICENSE.txt >> SCONS_SETUP_TYPE = distutils >> >> +HOST_SCONS_NEEDS_HOST_PYTHON = python3 > > I am just wondering if we should do our usual dance that consists in > relying on python2 if enabled, i.e something like this: > > HOST_SCONS_NEEDS_HOST_PYTHON = $(if ($(BR2_PACKAGE_PYTHON),python,python3) AFAIK, we usually do the opposite: $(if $(BR2_PACKAGE_PYTHON3),python3,python) > > or if we simply stop doing this and say that we switch to just python3 > > Titouan, what do you think ? In my very own opinion, we should now only use host-python3 everywhere, unless host-python(2) is strictly required. Pragmatically speaking, in the rare cases where host-python(2) is still necessary, having both Pythons on the host would not be that much of an overhead (both in terms of building time and disk space); and would reduce the clutter in all the places where we do the fancy dance you describe above. On the target side, I'm also looking forward to invert the target py2/py3 logic, ie changing $(if $(BR2_PACKAGE_PYTHON3),python3,python)) into $(if $(BR2_PACKAGE_PYTHON),python,python3)) especially in package/pkg-python.mk. Again, the goal is to have Python3 as default, while still allowing old Python2-only programs to run where needed. I'll try to find some time this week to go through the Buildroot tree and update the Python3 migration page (https://www.elinux.org/Buildroot:Python2Packages), as there has been some change since the FOSDEM dev days. This shall help us understand where Python2 is still required. > > Thomas > Titouan
On Tue, 14 Jul 2020 15:31:09 +0200 Titouan Christophe <titouan.christophe@railnova.eu> wrote: > > HOST_SCONS_NEEDS_HOST_PYTHON = $(if ($(BR2_PACKAGE_PYTHON),python,python3) > > AFAIK, we usually do the opposite: > $(if $(BR2_PACKAGE_PYTHON3),python3,python) Yes, but the idea is to reverse this progressively, and switch more and more to "Python 3.x" is the default. > In my very own opinion, we should now only use host-python3 everywhere, > unless host-python(2) is strictly required. Pragmatically speaking, in > the rare cases where host-python(2) is still necessary, having both > Pythons on the host would not be that much of an overhead (both in terms > of building time and disk space); and would reduce the clutter in all > the places where we do the fancy dance you describe above. I'm fine with moving towards host-python3 only where possible. > On the target side, I'm also looking forward to invert the target > py2/py3 logic, ie changing > > $(if $(BR2_PACKAGE_PYTHON3),python3,python)) > > into > > $(if $(BR2_PACKAGE_PYTHON),python,python3)) > > especially in package/pkg-python.mk. > > Again, the goal is to have Python3 as default, while still allowing old > Python2-only programs to run where needed. I'll try to find some time > this week to go through the Buildroot tree and update the Python3 > migration page (https://www.elinux.org/Buildroot:Python2Packages), as > there has been some change since the FOSDEM dev days. This shall help us > understand where Python2 is still required. That would be great indeed! Thomas
On 2020-07-14 2:15 a.m., Thomas Petazzoni wrote: > On Mon, 13 Jul 2020 21:39:27 -0600 > Robert Hancock <hancock@sedsystems.ca> wrote: > >> All packages using scons are now using Python 3 to run it, so >> explicitly set scons as using host-python3. This avoids a >> spurious host Python 2 dependency if BR2_PACKAGE_PYTHON3 is not >> set (for example, if no Python is packaged for the target). >> >> Signed-off-by: Robert Hancock <hancock@sedsystems.ca> >> --- >> package/scons/scons.mk | 2 ++ >> 1 file changed, 2 insertions(+) >> >> diff --git a/package/scons/scons.mk b/package/scons/scons.mk >> index da2ccceb08..a95fa7fd69 100644 >> --- a/package/scons/scons.mk >> +++ b/package/scons/scons.mk >> @@ -10,6 +10,8 @@ SCONS_LICENSE = MIT >> SCONS_LICENSE_FILES = LICENSE.txt >> SCONS_SETUP_TYPE = distutils >> >> +HOST_SCONS_NEEDS_HOST_PYTHON = python3 > > I am just wondering if we should do our usual dance that consists in > relying on python2 if enabled, i.e something like this: > > HOST_SCONS_NEEDS_HOST_PYTHON = $(if ($(BR2_PACKAGE_PYTHON),python,python3) > > or if we simply stop doing this and say that we switch to just python3. What you describe is basically the existing default behavior in package/pkg-python.mk when *_NEEDS_HOST_PYTHON is not set, except that the default is reversed, it defaults to python unless BR2_PACKAGE_PYTHON3 is set. The problem with that is it conflates what is selected for the target with what is needed on the host. In our configuration, no Python is selected for the target, so a dependency on host-python gets added, even though all of the packages using SCons explicitly depend on host-python3 and run SCons using python3, so the host-python dependency is pointless. I went with this simple change in the SCons case, as because it doesn't seem widely used (only 3 packages in Buildroot now), the chance that another package will end up being added that both uses SCons and can't use Python 3 to run it, seems quite unlikely. > > Titouan, what do you think ? > > Thomas >
On Mon, 13 Jul 2020 21:39:27 -0600 Robert Hancock <hancock@sedsystems.ca> wrote: > All packages using scons are now using Python 3 to run it, so > explicitly set scons as using host-python3. This avoids a > spurious host Python 2 dependency if BR2_PACKAGE_PYTHON3 is not > set (for example, if no Python is packaged for the target). > > Signed-off-by: Robert Hancock <hancock@sedsystems.ca> > --- > package/scons/scons.mk | 2 ++ > 1 file changed, 2 insertions(+) After so much time: patch applied! I also took the opportunity of your patch to do two scons-related changes: https://git.buildroot.org/buildroot/commit/?id=726209fc7999986fa414d629ff60d1bc76c63a2c https://git.buildroot.org/buildroot/commit/?id=c240410d4b38c7946d2dd65c1c1eec6d172a0814 Best regards, Thomas
diff --git a/package/scons/scons.mk b/package/scons/scons.mk index da2ccceb08..a95fa7fd69 100644 --- a/package/scons/scons.mk +++ b/package/scons/scons.mk @@ -10,6 +10,8 @@ SCONS_LICENSE = MIT SCONS_LICENSE_FILES = LICENSE.txt SCONS_SETUP_TYPE = distutils +HOST_SCONS_NEEDS_HOST_PYTHON = python3 + HOST_SCONS_INSTALL_OPTS = \ --install-lib=$(HOST_DIR)/lib/scons-$(SCONS_VERSION)
All packages using scons are now using Python 3 to run it, so explicitly set scons as using host-python3. This avoids a spurious host Python 2 dependency if BR2_PACKAGE_PYTHON3 is not set (for example, if no Python is packaged for the target). Signed-off-by: Robert Hancock <hancock@sedsystems.ca> --- package/scons/scons.mk | 2 ++ 1 file changed, 2 insertions(+)