Re: [PATCH bpf-next v2 4/4] LoongArch: Enable BPF_JIT and TEST_BPF in default config

[Tiezhu Yang <yangtiezhu@loongson.cn>]

On 09/01/2022 03:31 AM, Daniel Borkmann wrote:
> On 8/31/22 11:02 AM, Xi Ruoyao wrote:
>> On Wed, 2022-08-31 at 12:12 +0800, Xi Ruoyao wrote:
>>> On Wed, 2022-08-31 at 09:23 +0800, Tiezhu Yang wrote:
>>>>
>>>>
>>>> On 08/30/2022 10:46 PM, Huacai Chen wrote:
>>>>> Hi, Tiezhu,
>>>>>
>>>>> On Tue, Aug 30, 2022 at 7:10 PM Tiezhu Yang
>>>>> <yangtiezhu@loongson.cn> wrote:
>>>>>>
>>>>>> For now, BPF JIT for LoongArch is supported, update
>>>>>> loongson3_defconfig to
>>>>>> enable BPF_JIT to allow the kernel to generate native code when
>>>>>> a program
>>>>>> is loaded into the kernel, and also enable TEST_BPF to test BPF
>>>>>> JIT.
>>>>>>
>>>>>> Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
>>>>>> ---
>>>>>>   arch/loongarch/configs/loongson3_defconfig | 2 ++
>>>>>>   1 file changed, 2 insertions(+)
>>>>>>
>>>>>> diff --git a/arch/loongarch/configs/loongson3_defconfig
>>>>>> b/arch/loongarch/configs/loongson3_defconfig
>>>>>> index 3712552..93dc072 100644
>>>>>> --- a/arch/loongarch/configs/loongson3_defconfig
>>>>>> +++ b/arch/loongarch/configs/loongson3_defconfig
>>>>>> @@ -4,6 +4,7 @@ CONFIG_POSIX_MQUEUE=y
>>>>>>   CONFIG_NO_HZ=y
>>>>>>   CONFIG_HIGH_RES_TIMERS=y
>>>>>>   CONFIG_BPF_SYSCALL=y
>>>>>> +CONFIG_BPF_JIT=y
>>>>>>   CONFIG_PREEMPT=y
>>>>>>   CONFIG_BSD_PROCESS_ACCT=y
>>>>>>   CONFIG_BSD_PROCESS_ACCT_V3=y
>>>>>> @@ -801,3 +802,4 @@ CONFIG_MAGIC_SYSRQ=y
>>>>>>   CONFIG_SCHEDSTATS=y
>>>>>>   # CONFIG_DEBUG_PREEMPT is not set
>>>>>>   # CONFIG_FTRACE is not set
>>>>>> +CONFIG_TEST_BPF=m
>>>>> I don't want the test module be built by default, but I don't
>>>>> insist
>>>>> if you have a strong requirement.
>>>>>
>>>>
>>>> Hi Huacai,
>>>>
>>>> It is useful to enable TEST_BPF in default config, otherwise we
>>>> need to use "make menuconfig" to select it manually if we want
>>>> to test bpf jit, and build it as a module by default has no side
>>>> effect, so I prefer to enable TEST_BPF in default config.
>>>
>>> IMO we shouldn't enable a test feature which is never used by 99% of
>>> users in the default.
>>
>> P. S. this is not a strong option.  CONFIG_TEST_BPF seems enabled by
>> default for S390, and I'm not sure if defconfig is designed for "kernel
>> developers" or "distro builders", or even "normal users".
>
> Right now BPF CI [0] tests x86_64 and s390x archs, would be nice to also
> add others in future to increase test coverage and then include test_bpf
> as part of the executed test suites. If noone beats me to it, the latter
> still sits in my bucket list. But either way, that would make more sense
> than adding CONFIG_TEST_BPF to defconfig. Looks like for odd reasons m68k
> and s390x has it, it shouldn't be there, really.
>
> Thanks,
> Daniel
>
>   [0] https://github.com/kernel-patches/bpf/pulls

OK, it is clear now, let me remove CONFIG_TEST_BPF in
loongson3_defconfig, thank you all.

Thanks,
Tiezhu