Re: [PATCH v4 bpf] kbuild: fix dependencies for DEBUG_INFO_BTF

Slava Bacherikov
2020-04-02T20:38:42Z

02.04.2020 23:34, Kees Cook wrote:
> On Thu, Apr 02, 2020 at 12:31:36PM -0700, Andrii Nakryiko wrote:
>> On Thu, Apr 2, 2020 at 8:40 AM Slava Bacherikov <slava@bacher09.org> wrote:
>>>
>>>
>>>
>>> 02.04.2020 18:33, Slava Bacherikov wrote:
>>>> + depends on DEBUG_INFO || COMPILE_TEST
>>>
>>> Andrii are you fine by this ?
>>
>> I think it needs a good comment explaining this weirdness, at least.
>> As I said, if there is no DEBUG_INFO, there is not point in doing
>> DWARF-to-BTF conversion, even more -- it actually might fail, I
>> haven't checked what pahole does in that case. So I'd rather drop
>> GCC_PLUGIN_RANDSTRUCT is that's the issue here. DEBUG_INFO_SPLIT and
>> DEBUG_INFO_REDUCED look good.

Yesterday before sending it I tested it against latest bpf git with
allyesconfig and it compiled fine, even worked in vm ;)
>
> The DEBUG_INFO is separate, AIUI -- it sounds like BTF may entirely
> break on a compile with weird DWARF configs.
>
> The GCC_PLUGIN_RANDSTRUCT issue is separate: it doesn't make sense to
> run a kernel built with BTF and GCC_PLUGIN_RANDSTRUCT. But they should
> have nothing to do with each other with regard to compilation. So, to
> keep GCC_PLUGIN_RANDSTRUCT disable for "real" builds but leave it on for
> all*config, randconfig, etc, I'd like to keep the || COMPILE_TEST,
> otherwise GCC_PLUGIN_RANDSTRUCT won't be part of the many CIs doing
> compilation testing.
>
> And FWIW, I'm fine to let GCC_PLUGIN_RANDSTRUCT and BTF build together.
> But if they want to be depends-conflicted, I wanted to keep the test
> compile trap door.
>

Oh, seems I misunderstood you, if everyone agree I'll drop it.