Re: [RFC PATCH] tests/vm: avoid re-building the VM images all the time

[Peter Maydell]

On Mon, 26 Feb 2024 at 18:06, Alex Bennée <alex.bennee@linaro.org> wrote:
>
> Alex Bennée <alex.bennee@linaro.org> writes:
>
> > There are two problems.
> >
> > The first is a .PHONY target will always evaluate which triggers a
> > full re-build of the VM images. Drop the requirement knowing that this
> > introduces a manual step on freshly configure build dirs.
> >
> > The second is a minor unrelated tweak to the Makefile also triggers an
> > expensive full re-build. Solve this be avoiding the dependency and
> > putting a comment just above the bit that matters and hope developers
> > notice the comment.
> >
> > Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
> >
> > ---
> >
> > This is hacky and sub-optimal. There surely must be a way to have our cake
> > and eat it?
> > ---
> >  tests/vm/Makefile.include | 7 ++++---
> >  1 file changed, 4 insertions(+), 3 deletions(-)
> >
> > diff --git a/tests/vm/Makefile.include b/tests/vm/Makefile.include
> > index bf12e0fa3c5..a109773c588 100644
> > --- a/tests/vm/Makefile.include
> > +++ b/tests/vm/Makefile.include
> > @@ -88,10 +88,11 @@ vm-build-all: $(addprefix vm-build-, $(IMAGES))
> >  vm-clean-all:
> >       rm -f $(IMAGE_FILES)
> >
> > +# Rebuilding the VMs every time this Makefile is tweaked is very
> > +# expensive for most users. If you tweak the recipe bellow you will

"below".

But how many people edit tests/vm/Makefile.include ?
It had only 5 changes made to it last year. At that
frequency of changes I think I'd favour "always do the
right thing" over "require manual removal of the cached
image sometimes".

thanks
-- PMM