linux-kernel - Re: [PATCH v3 0/2] Don't create Python bytecode when building the kernel

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Message-ID: <aAoERIArkvj497ns@smile.fi.intel.com>
Date: Thu, 24 Apr 2025 12:28:36 +0300
From: Andy Shevchenko <andriy.shevchenko@...el.com>
To: Akira Yokosawa <akiyks@...il.com>
Cc: airlied@...il.com, corbet@....net, dmitry.baryshkov@....qualcomm.com,
	dri-devel@...ts.freedesktop.org, intel-gfx@...ts.freedesktop.org,
	jani.nikula@...ux.intel.com, joonas.lahtinen@...ux.intel.com,
	linux-doc@...r.kernel.org, linux-kbuild@...r.kernel.org,
	linux-kernel@...r.kernel.org, maarten.lankhorst@...ux.intel.com,
	masahiroy@...nel.org, mchehab+huawei@...nel.org, mripard@...nel.org,
	nathan@...nel.org, nicolas.schier@...ux.dev, rodrigo.vivi@...el.com,
	simona@...ll.ch, tursulin@...ulin.net, tzimmermann@...e.de
Subject: Re: [PATCH v3 0/2] Don't create Python bytecode when building the
 kernel

On Thu, Apr 24, 2025 at 11:07:05AM +0900, Akira Yokosawa wrote:
> On Wed, 23 Apr 2025 19:31:36 +0300, Andy Shevchenko wrote:
> > On Wed, Apr 23, 2025 at 06:30:48PM +0900, Akira Yokosawa wrote:
> >> On Tue, 22 Apr 2025 10:57:33 +0300, Andy Shevchenko wrote:
> >>> On Mon, Apr 21, 2025 at 10:35:29AM -0600, Jonathan Corbet wrote:
> >>>> Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com> writes:

[...]

> >>>>> Would it be possible to properly support O= and create pyc / pycache
> >>>>> inside the object/output dir?
> >>>>
> >>>> I have to confess, I've been wondering if we should be treating the .pyc
> >>>> files like we treat .o files or other intermediate products.  Rather
> >>>> than trying to avoid their creation entirely, perhaps we should just be
> >>>> sure they end up in the right place and are properly cleaned up...?
> >>>>
> >>>> To answer Dmitry's question, it seems that setting PYTHONPYCACHEPREFIX
> >>>> should do the trick?
> >>>
> >>> It's not so easy. The Python is written in a way that it thinks it will never
> >>> runs object files separately from the source. Hence that variable sets only
> >>> the folder per script as _home_ for the cache. It's completely unusable. They
> >>> took it wrong. It still can be _painfully_ used, but it will make Makefiles
> >>> uglier.
> >>
> >> But, PYTHONPYCACHEPREFIX can be set as an environment variable.
> >>
> >> For example, try:
> >>
> >>     export PYTHONPYCACHEPREFIX="$HOME/.cache/__pycache__"
> >>
> >> Wouldn't it be good enough for you?
> > 
> > Of course not. We have _many_ scripts in python in kernel and having a cache
> > there for _all_ of them is simply WRONG. You never know what clashes can be
> > there with two complicated enough scripts which may have same module names,
> > etc.
> 
> Interesting...
> 
> I'm suspecting you replied without having tried the setting...

I tried before, but I admit, that I have missed something. It was a mess
in that case. Now I probably can't repeat as I don't remember what was
the environment and settings I had that time. I'm really glad to see it
is working this way!

-- 
With Best Regards,
Andy Shevchenko