On 10/21/20 3:36 PM, Theodore Y. Ts'o wrote:
> On Wed, Oct 21, 2020 at 02:16:56PM -0700, Randy Dunlap wrote:
>> On 10/21/20 2:15 PM, Brendan Higgins wrote:
>>> On Tue, Oct 20, 2020 at 12:37 AM Geert Uytterhoeven
>>> <geert@xxxxxxxxxxxxxx> wrote:
>>>>
>>>> EXT4_KUNIT_TESTS selects EXT4_FS, thus enabling an optional feature the
>>>> user may not want to enable. Fix this by making the test depend on
>>>> EXT4_FS instead.
>>>>
>>>> Fixes: 1cbeab1b242d16fd ("ext4: add kunit test for decoding extended timestamps")
>>>> Signed-off-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
>>>
>>> If I remember correctly, having EXT4_KUNIT_TESTS select EXT4_FS was
>>> something that Ted specifically requested, but I don't have any strong
>>> feelings on it either way.
>>
>> omg, please No. depends on is the right fix here.
>
> So my requirement which led to that particular request is to keep what
> needs to be placed in .kunitconfig to a small and reasonable set.
>
> Per Documentation/dev-tools/kunit, we start by:
>
> cd $PATH_TO_LINUX_REPO
> cp arch/um/configs/kunit_defconfig .kunitconfig
>
> we're then supposed to add whatever Kunit tests we want to enable, to wit:
>
> CONFIG_EXT4_KUNIT_TESTS=y
>
> so that .kunitconfig would look like this:
>
> CONFIG_KUNIT=y
> CONFIG_KUNIT_TEST=y
> CONFIG_KUNIT_EXAMPLE_TEST=y
> CONFIG_EXT4_KUNIT_TESTS=y
>
> ... and then you should be able to run:
>
> ./tools/testing/kunit/kunit.py run
>
> ... and have the kunit tests run. I would *not* like to have to put a
> huge long list of CONFIG_* dependencies into the .kunitconfig file.
>
> I'm don't particularly care how this gets achieved, but please think
> about how to make it easy for a kernel developer to run a specific set
> of subsystem unit tests. (In fact, being able to do something like
> "kunit.py run fs/ext4 fs/jbd2" or maybe "kunit.py run fs/..." would be
> *great*. No need to fuss with hand editing the .kunitconfig file at
> all would be **wonderful**.
I understand the wish for ease of use, but this is still the tail
wagging the dog.
The primary documentation for 'select' is
Documentation/kbuild/kconfig-language.rst, which says:
Note:
select should be used with care. select will force
a symbol to a value without visiting the dependencies.
By abusing select you are able to select a symbol FOO even
if FOO depends on BAR that is not set.
In general use select only for non-visible symbols
(no prompts anywhere) and for symbols with no dependencies.
That will limit the usefulness but on the other hand avoid
the illegal configurations all over.
--
~Randy
