Re: [PATCH] libbpf: allow bpf object kern_version to be overridden

[Rafael David Tinoco <rafaeldtinoco@ubuntu.com>]

>>>
>>> This will also help portable binaries within similar older kernels, as
>>> long as they have their BTF data converted from DWARVES (for example).
>>>
>>> Signed-off-by: Rafael David Tinoco <rafaeldtinoco@ubuntu.com>
>>> ---
>> Libbpf currently provides a way to specify custom kernel version using
>> a special "version" ELF section:
>> int _version SEC("version") = 123;
>> But it seems like you would want to set it at runtime, so this
>> compile-time approach might be problematic. But instead of hijacking
>> get_kernel_version(), it's better to add a simple setter counterpart
>> to bpf_object__kversion() that would just override obj->kern_version.
>
> +1, agree, setter makes sense for old kernels, so the loader app can set/
> retrieve from wherever it's needed. In addition, couldn't you also backport
> the old commit that ignores the kern_version from kernel side (won't help
> existing users, but at least might simplify things once they start  
> upgrade)?

Yep :\ that was my initial approach and I went for something simpler.
Will propose something else. Once I finish this, I’ll propose the
back-ports removing the version check to the kernel team. Not having
the attr version check will definitely help this, for now needed,
mitigation to fade away.

Thanks for the reviews, would appreciate comments on:

[RFC][PATCH] libbpf: support kprobe/kretprobe events in legacy environments

if possible, as both walk together supporting legacy kernels.

tks
-rafaeldtinoco