Leif: I agree to discuss the behavior first, then review the code logic in detail. I add my comments below.
> -----Original Message----- > From: Leif Lindholm [mailto:leif.lindh...@linaro.org] > Sent: Wednesday, July 17, 2019 6:05 AM > To: Laszlo Ersek <ler...@redhat.com> > Cc: devel@edk2.groups.io; Rebecca Cran <rebe...@bsdio.com>; Feng, Bob C > <bob.c.f...@intel.com>; Gao, Liming > <liming....@intel.com>; Kinney, Michael D <michael.d.kin...@intel.com>; > af...@apple.com > Subject: Re: [PATCH 1/1] edksetup.sh: rework python executable scanning > > On Tue, Jul 16, 2019 at 10:49:03PM +0200, Laszlo Ersek wrote: > > Hi Leif, > > > > On 07/16/19 21:07, Leif Lindholm wrote: > > > If PYTHON_COMMAND is set, use that. > > > If PYTHON_COMMAND is not set, use first working of "python", "python3", > > > "python2". > > > If none of those work, search the path for python*[0-9], using the > > > highest version > > > number across x.y.z format. > > > > > > Finally, set PYTHON3_ENABLE if selected python is python 3. > > > > > > Signed-off-by: Leif Lindholm <leif.lindh...@linaro.org> > > > --- > > > > > > This is my somewhat overkill proposal as an alternative to Rebecca's 5/6. > > > It is certainly more complex than that patch, and arguably as complex as > > > the current upstream implementation, but the semantics and flow is more > > > clear (to me, at least). > > > > > > An alternative version to *this* patch would be one that drops the > > > FindHighestVersionedExecutable() function, and the if-statement that > > > calls it. This would still leave us with a solution that would use (in > > > order): > > > * PYTHON_COMMAND > > > * python > > > * python3 > > > * python2 > > > and fail with an error if $PYTHON_COMMAND (if set externally) or none of > > > the > > > others could execute $PYTHON_COMMAND --version. > > > > I think I'd be fine, personally, with this change. It's still a > > behavioral change in two aspects, and so I'd like the BaseTools > > maintainers to comment on those: > > Likewise. > > > (1) If I understand correctly, the proposed patch would favor "python" > > (no version number) over "python3". That diverges from current practice. > > Yes. And in fact this is one of the things I found problematic (but not > seriously so) with the functionality that is currently in the tree. > > > I think this is a relevant question because the BaseTools maintainers > > prefer python3 over python2, if a system offers both, even if the system > > default "python" points to "python2". > > > > I deduce this claim from > > <https://lists.01.org/pipermail/edk2-devel/2018-December/034459.html>: > > > > "we have no enough resource to fully verify Python2 and Python3 both. We > > will focus on Python3 validation. If anyone can help verify Python2, it > > will be great. And, if you meet with the issue on Python2, please file > > BZ. We still fix them." > > > > So the primary target seems to be python3; considered "more thoroughly > > validated" at all times (my words). > > Yes, but likewise, a system may have more properly validated (and > certainly more likely to have common required modules installed for) > the python installed as "python". This applies even more so with CI > builders running docker images, since whoever configures those is more > likely than an end-user to change distribution default. > > Important point here being that overriding the default behaviour is as > easy as PYTHON_COMMAND=python3. > > > (2) The original proposal (see it included e.g. in > > <https://lists.01.org/pipermail/edk2-devel/2019-January/035815.html>) > > gave some significance to the PYTHON3_ENABLE variable (coming from the > > user's environment). Doesn't this patch erase that? > > Oh, was that was that was for? I couldn't really figure it out > (especially w.r.t. relationship with the same in build.py). > > > ( > > > > Looking back at that specification -- I basically don't understand what > > PYTHON3_ENABLE=TRUE was supposed to stand for, coming from the user's env. > > You and me both :) > > > I do understand the other two cases: PYTHON3_ENABLE unset, plus > > PYTHON_COMMAND either set or unset. This last variation is actually what > > my question (1) concerns. > > > > ) > > > > > > Furthermore, > > > > (3) after looking at FindHighestVersionedExecutable(), I think I would > > prefer the variant of this patch -- assuming the behavioral change is OK > > in the first place -- that does not have > > FindHighestVersionedExecutable(). It's not that > > FindHighestVersionedExecutable() is too complex -- the problem is that > > the function is complex *and* a good chunk of it will never be used in > > practice. I doubt we have to prepare for python4 or python5 at this > > point. Similarly for patch levels. > > So, first of all - I am entirely happy with dropping the function. > But I wanted to have it written anyway in case someone came up with a > really good explanation for why we needed to completely cover the same > pattern as the code currently in tree: and the situation does not > relate to python4 or python5 - it relates to picking the latest of > 2.7, 2.7.6, 3.5, 3.5.2, 3.5,4, 3.7 (which is my interpretation of the > behaviour of current HEAD). > > So basically - I think we need to reach an agreement (with BaseTools > maintainers, and existing users) about what the behaviour should be. > > - What does PYTHON3_ENABLE mean? Is it for probing only, or are we > setting it for later use by BaseTools? PYTHON3_EANBLE is to decide python3 enable or not. It has high priority. Once it is set, PYTHON_COMMAND will be ignored. If it is set to TRUE, edksetup.sh will find Python3 in the system, set PYTHON_COMMAND env. If it is set to other value, edksetup.sh will find Python3 in the system, set PYTHON_COMMAND env. If PYTHON3_EANBLE is not set, PYTHON_COMMAND will be used if PYTHON_COMMAND is set. If PYTHON3_EANBLE is not set, and PYTHON_COMMAND is not set, the default behavior will set PYTHON3_EANBLE to TRUE. So, the default behavior is to use highest version Python3. User can set PYTHON_COMMAND for their python version. > - What should the priority order be when looking for python > executables? Find the high version python. When we enable Python3, we find Python37 does great performance optimization. So, we think high version python can bring more benefit. > - Can we use simply 'python' as the default? Based on previous discussion, we recommend to use Python3 as default. > - Do we need functionality for more than selecting between > python2/python3? Yes. Find the high version python installed in the system. Thanks Liming > > If we don't _need_ to support anything beyond python2 and python3 > (other than overriding with PYTHON_COMMAND), then including > FindHighestVersionedExecutable() would be outright silly. > > > I believe one thing I like about Rebecca's 5/6 is that, while it does > > check for some surprisingly high (and arbitrary) minor releases -- such > > as python3.15, python2.10 --, the loops are really small and simple. No > > extra complexity is needed for covering all practically relevant > > releases. In case we ever exceeded "python3.15", it would take a > > one-liner to bump the limit (and it would take a simple patch to factor > > out the loop to a function, and check for python4.[0..15] even). > > I dislike arbitrary limits, and planned maintenance overhead (no > matter how trivial). If we only need to worry about picking python2 or > python3, then we can both be happy. > > Best Regards, > > Leif -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#43837): https://edk2.groups.io/g/devel/message/43837 Mute This Topic: https://groups.io/mt/32495132/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
