On 11/21/23 12:36, David Gow wrote:
Thanks so much for doing this! I think everyone agrees that we need
_some_ way of documenting which tests to run, and I think this is our
best option.
Awesome :D
In any case, this patch does a lot, and I'll comment on them
one-by-one. (It may be worth splitting this patch up into a few
separate bits, if only so that we can better separate the
uncontroversial bits from the open questions.)
Yeah, I'll try to figure out a less controversial split.
On Thu, 16 Nov 2023 at 01:52, Nikolai Kondrashov
Each referenced test suite is expected to be documented in the new
Documentation/process/tests.rst file, which must have enough structure
(documented inside) for the tools to make use of it. Apart from basic
data, each test can refer to its "superset" - a test suite which this
one is a part of. The expected use is to describe both a large test
suite and its subsets, so the former would also be accepted, if a
subsystem requires only a subset.
I think this could work, but is a bit complicated.
My initial thought was to have this as a more free-form field, which
either contained a:
- Path to a command to run (e.g. tools/testing/kunit/run_checks.py)
- Path to a documentation file describing the test.
- URL to a page describing the test
- (Maybe) freeform text.
I think we should be careful about having too much flexibility here, if we
want to have tools process this. I mean, we would then have to formalize and
define the syntax for all the cases, which could then become too obscure for
humans to easily read and write.
As I said elsewhere, our ultimate (even if unachievable) target should be to
have commands to execute (instead of long setup and execution instructions),
for *all* V: entries. So that definitely should be supported. The current
patch already supports putting a command in the tests.rst to be printed by
checkpatch.pl. Perhaps we can allow putting it into the V: entry directly. I
have one idea on how to do that.
OTOH, I think there's value in an overall catalogue of tests and having
easily-accessible documentation for that command (even if brief), and that's
what going for the command via tests.rst allows.
Regarding a path to the documentation file, that goes against the idea of a
catalogue file, again, so I'm reluctant of letting it go. Same goes for a
documentation URL. Both of these can be expressed via the catalogue too.
I wonder if it could be useful to add another option to get_maintainer.pl, or
implement a new script, which would just dump the referenced test catalogue
sections for a patchset, for a longer-form read than what checkpatch.pl can
produce, but faster than scanning the whole catalogue personally.
It's probably worth also looking at this proposal to auto-generate
similar documentation:
https://lore.kernel.org/linux-kselftest/cover.1689171160.git.mchehab@xxxxxxxxxx/
IIRC, Mauro has mentioned this effort to me at EOSS in Prague, but I still
haven't found the time to look at it closely. I think this is a worthy effort
overall, but at a somewhat lower level. What I would like to be in the
tests.rst is a basic intro and help to get each corresponding test suite
running, to help breach the gap between trying to contribute and having your
contribution tested with what maintainers prescribe. The docs in tests.rst can
point to the more detailed docs, in turn. I also think it's good to have a
document with an overview of what tests exist in general and which areas they
address.
The other question is how to handle outdated results when a new patch
revision is sent out. Personally, I think this is something we can
solve similarly to 'Reviewed-by', depending on the extent of the
changes and cost of the tests. I suspect for most automated tests,
this would mean never carrying the 'Tested-with' tag over, but if
testing it involved manually building and running kernels against 50
different hardware setups, I could imagine it making sense to not
re-do this if a new revision just changed a doc typo. If a URL is used
here, it could contain version info, too.
Yeah, that would be painful.
Paste encouragement for in-tree test suites triggered by git forges here <
I think what Ricardo is suggesting in another branch, regarding adding result
URLs, could work. So it would be nice to account for that in the change, but
the policy would probably depend on subsystem/maintainer/the change in question.
Introduce a new tag, 'Tested-with:', documented in the
Documentation/process/submitting-patches.rst file. The tag is expected
to reference the documented test suites, similarly to the 'V:' field,
and to certify that the submitter executed the test suite on the change,
and that it passed.
I'm also 100% for this, though I'd considered it separately from the
MAINTAINERS change.
I think, in the ideal case, we want this to link to the results
somehow. kcidb would seem to be the obvious choice there.
Again, as a fallback, a plain text field would be useful to describe
cases where a patch was tested by some means other than a formal test
suite. This might not be ideal, but I'd still rather have people
describe that something "builds and boots on <x> hardware" than have
to guess if a patch was tested at all.
Of course, it'd then be up to maintainers to decide what they'd
accept: I'd expect that some would require there be a 'Tested-with'
header which links to valid results for the tests described in
MAINTAINERS.
I'm thinking that maybe we should just not *require* a valid reference to a
documented test in the Tested-with: field. I.e. only verify that all the V:
values are listed, but ignore everything unknown.
Make scripts/checkpatch.pl ensure any added V: fields reference
documented test suites only, and output a warning if a change to a
subsystem doesn't certify the required test suites were executed,
if any.
I'd definitely want something like this to run at some point in the
patch-submission workflow. I think that, ultimately, we'll want to be
able to run some tests automatically (e.g., a git hook could run the
tests and add the 'Tested-with' line).
Personally, I'd like to require that all patches have a 'Tested-with'
field, even if there's not a corresponding 'V' MAINTAINERS entry, as
people should at least think of how something's tested, even if
there's not a formal 'test suite' for it. Though that seems a
longer-term goal
Yeah, that would be nice from a maintainer's POV, but probably not very popular.
If the test suite description includes a "Command", then checkpatch.pl
will output it as the one executing the suite. The command should run
with only the kernel tree and the regular developer environment set up.
But, at the same time, could simply output instructions for installing
any extra dependencies (or pull some automatically). The idea is to
get the developer into feedback loop quicker and easier, so they have
something to run and iterate on, even if it involves installing some
more stuff first. Therefore it's a good idea to add such wrappers to the
kernel tree proper and refer to them from the tests.rst.
Extend scripts/get_maintainer.pl to support retrieving the V: fields,
and scripts/parse-maintainers.pl to maintain their ordering.
Signed-off-by: Nikolai Kondrashov <Nikolai.Kondrashov@xxxxxxxxxx>
---
The questions I think we need to answer to get this in are:
1. Do we want to split this up (and potentially land it
piece-by-piece), or is it more valuable to have a stricter, more
complete system from the get-go?
I'll see what I can do about splitting it.
2. What format should the 'V' line take? If it is simply a test name,
do we use a doc as suggested (or one generated in part from some other
process), or something like a command name or URL? Can it just be
freeform text?
3. Should 'Tested-with' be a test name in the same format as 'V', a
URL to results (any URL, or just kcidb?), or freeform text? How does
this evolve with multiple versions of patches?
I don't think it's useful to restrict this to kcidb. I think the tools should
generally allow anything there, but verify the entries by MAINTAINERS are
there, as I write above.
4. How should this be enforced? A warning (not an 'error') from
checkpatch? A separate script?
Personally, my gut feeling is that we should land the simplest, most
minimal version of this (the 'V' field, as freeform text) now, and
build on that as consensus and tooling permits. I'd probably also add
the 'Tested-with' or similar tag, as freeform text, too. I don't think
either of those would cause major problems if we needed to change or
restrict the format later; I imagine there won't be a huge need to
parse old commits for test data, and even if so, it wouldn't be too
hard to ignore any which don't conform to any stricter future
convention.
But I don't think there's anything fundamentally wrong with the full
plan as-is, so if everyone's happy with it, I'd not object to having
it.
I agree that the minimum support (just the freeform V:/Tested-with:) would be
easier to get merged, but would also be somewhat toothless. I think some sort
of test documentation/catalogue adds value, and a message from checkpatch.pl
even more so, as it greatly aids test discoverability, and I is a major point
of the change. We can lower the WARN to INFO to reduce resistance, or even
maybe make the level configurable in the V: field.
Anyway, I'll work on splitting this.
Thanks a lot for the extensive and insightful comments, David!
Nick
