From: Andrii Nakryiko <andriin@fb.com>
To: Liu Yiding <liuyd.fnst@cn.fujitsu.com>
Cc: <linux-kselftest@vger.kernel.org>,
"bpf@vger.kernel.org" <bpf@vger.kernel.org>,
"andrii.nakryiko@gmail.com" <andrii.nakryiko@gmail.com>
Subject: Re: runqslower build failed on Debian9
Date: Sun, 29 Mar 2020 23:09:55 -0700 [thread overview]
Message-ID: <a2b1a025-6a70-c3a5-fc19-155f0266946a@fb.com> (raw)
In-Reply-To: <a2771f66-b7ff-f320-dbd6-0967c189834f@cn.fujitsu.com>
On 3/29/20 5:48 PM, Liu Yiding wrote:
> Add attachment.
>
Your BTF seems to be invalid. It has struct perf_ibs, which has a first
field `struct pmu pmu` field with valid-looking size of 296 bytes,
**but** the type that field points to is not a complete `struct pmu`
definition, but rather just forward declaration. The way it is it
shouldn't be even compilable, because forward declaration of a struct
doesn't specify the size of a struct, so compiler should have rejected
it. So it must be that either DWARF generated by compiler isn't correct,
or there is DWARF -> BTF conversion bug somewhere. Are you using any
special DWARF Kconfig settings? Maybe you can share your full .config
and I might try to repro it on my machine.
But either way, that warning you get is a valid one, it should be
illegal to have non-pointer forward-declared struct as a type for a
struct member.
>
> On 3/30/20 8:46 AM, Liu Yiding wrote:
>> Something wrong with my smtp and this email missed.
>>
>> Send again.
>>
>>
>> On 3/27/20 11:09 AM, Liu Yiding wrote:
>>> Hi, Andrii.
>>>
>>> Thanks for your prompt reply!
>>>
>>> Please check attatchment for my_btf.bin.
>>>
>>>
>>> On 3/27/20 4:28 AM, Andrii Nakryiko wrote:
>>>> Would you be able to share BTF of vmlinux that is used to generate
>>>> vmlinux.h? Please run in verbose mode: `make V=1` and search for
>>>> `bpftool btf dump file` command. It should point either to
>>>> /sys/kernel/btf/vmlinux or some other location, depending on how
>>>> things are set up on your side.
>>>>
>>>> If it's /sys/kernel/btf/vmlinux, you can just `cat
>>>> /sys/kernel/btf/vmlinux > my_btf.bin`. If it's some other file,
>>>> easiest would be to just share that file. If not, it's possible to
>>>> extract .BTF ELF section, let me know if you need help with that.
>>>
next prev parent reply other threads:[~2020-03-30 6:10 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <60b05d23-6352-b978-3bf7-5a86466bb297@cn.fujitsu.com>
2020-03-26 20:28 ` runqslower build failed on Debian9 Andrii Nakryiko
[not found] ` <84a70348-62e3-728b-d934-28e902d40fd0@cn.fujitsu.com>
2020-03-30 0:46 ` Liu Yiding
[not found] ` <a2771f66-b7ff-f320-dbd6-0967c189834f@cn.fujitsu.com>
2020-03-30 6:09 ` Andrii Nakryiko [this message]
[not found] ` <7705ca15-0d63-2e17-b947-51852c196c4b@cn.fujitsu.com>
2020-03-31 19:47 ` Andrii Nakryiko
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