[llvm-dev] BPF: How can I enable BPF support in my LLVM toolchain?

[Tom Stellard via llvm-dev]

On 1/11/21 9:11 AM, Sedat Dilek wrote:
> On Mon, Jan 11, 2021 at 4:35 PM Tom Stellard <tstellar at redhat.com> wrote:
>>
>> On 1/11/21 5:35 AM, Sedat Dilek via llvm-dev wrote:
>>> Hi,
>>>
>>> when building a Linux-kernel with CONFIG_DEBUG_INFO_BTF=y my build breaks.
>>>
>>
>> I commented on the GitHub issue about the root cause of this.
>>
>>> This is because my selfmade LLVM toolchain v11.0.1 has no BPF support:
>>>
>>> $ llc --version
>>> LLVM (http://llvm.org/):
>>>    LLVM version 11.0.1
>>>    Optimized build.
>>>    Default target: x86_64-unknown-linux-gnu
>>>    Host CPU: sandybridge
>>>
>>>    Registered Targets:
>>>      x86    - 32-bit X86: Pentium-Pro and above
>>>      x86-64 - 64-bit X86: EM64T and AMD64
>>>
>>> What system or binary requirements do I need and which CMAKE option(s)
>>> need(s) to be set?
>>
>> The LLVM_TARGETS_TO_BUILD CMake option controls which targets to build.
>>
> 
> tc-build folks fixed that up.
> See commit "build-llvm.py: Enable BPF backend by default".
> 
> Is there a BPF test-suite - like for clang and lld?
> 

There's one in the kernel.

-Tom

> I have build pahole from Git - now building a new Linux kernel.
> 
> $ cd /path/to/pahole/git
> $ git describe
> v1.19-7-gb688e3597060
> 
> Will report later.
> 
> Regards,
> - Sedat -
> 
> [1] https://github.com/ClangBuiltLinux/tc-build/commit/e796c046428a971404eec008c841f9dd7c1621e8
> 
>> -Tom
>>
>>> I hope this is not hardware-dependent (here: Intel SandyBridge).
>>>
>>> Thanks in advance.
>>>
>>> Regards,
>>> - Sedat -
>>>
>>> [1] https://github.com/ClangBuiltLinux/tc-build/issues/129
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>>>
>>
>