[OE-core] non-standard library locations and rpath

[Khem Raj]

On Mon, Dec 5, 2016 at 9:41 AM, Jack Mitchell <ml at embed.me.uk> wrote:
>
>
> On 05/12/16 16:43, Khem Raj wrote:
>>
>> On Mon, Dec 5, 2016 at 2:54 AM, Jack Mitchell <ml at embed.me.uk> wrote:
>>>
>>>
>>>
>>> On 05/12/16 10:44, Jack Mitchell wrote:
>>>>
>>>>
>>>> On 02/12/16 07:08, Khem Raj wrote:
>>>>>
>>>>>
>>>>> On Thu, Dec 1, 2016 at 8:18 AM, Jack Mitchell <ml at embed.me.uk> wrote:
>>>>>>
>>>>>>
>>>>>> I'm having some troubles with shared library, shared library
>>>>>> dependencies
>>>>>> and rpaths. I have libfoo, which depends on libbar when I try to link
>>>>>> libfoo
>>>>>> with my app, it requires libbar to be found. libbar is in a
>>>>>> non-standard
>>>>>> location, /usr/local/bar when I compiled libfoo, I used -Wl,rpath-link
>>>>>> ${STAGING_SYSROOT}/usr/local/bar and -Wl,rpath /usr/local/bar. Now
>>>>>> when I
>>>>>> come to try link my app with libfoo, it fails to link as it can't find
>>>>>> libbar, which I assume means the rpath in libfoo isn't being properly
>>>>>> prepending with sysroot what is the proper way to support this in OE?
>>>>>> My
>>>>>> library has the following rpath information:
>>>>>>
>>>>>> 0x0000000f (RPATH) Library rpath: [$ORIGIN/../lib:/usr/local/bar]
>>>>>>
>>>>>> So why isn't the rpath being prepended with the sysroot when I
>>>>>> compile my
>>>>>> app and link libfoo? The apps build system is using cmake, but this
>>>>>> should
>>>>>> be a built in linker feature, correct?
>>>>>
>>>>>
>>>>>
>>>>> Only first path ( before :) is relative to location of binary at
>>>>> runtime
>>>>>
>>>>
>>>> Exactly, so how can you make an OE build use the rpaths of libs that
>>>> point to the build sysroot. What I have at the moment is
>>>>
>>>> 0x0000000f (RPATH) Library rpath: [$ORIGIN/../lib:/usr/local/bar]
>>>>
>>>> Which would be correct if I was linking on the target. However when OE
>>>> sees the rpath in it's cross compile environment it should prepend it
>>>> with the build sysroot so you end up with something like
>>>>
>>>> 0x0000000f (RPATH) Library rpath:
>>>> [$ORIGIN/../lib:/path/to/build/sysroot/usr/local/bar]
>>>>
>>>> And then the SDK should end up with something like
>>>>
>>>> 0x0000000f (RPATH) Library rpath:
>>>> [$ORIGIN/../lib:/path/to/sdk/sysroot/usr/local/bar]
>>>>
>>>> Is this what is expected to happen, or am I stumbling into an
>>>> unsupported scenario.
>>>>
>>>> Cheers,
>>>
>>>
>>>
>>> I think basically what I'm saying is that does the linker prepend it's
>>> --sysroot value to absolute rpaths, and if not, should it?
>>
>>
>> having absolute build paths into rpaths is not a good thing. Linker
>> will search the libs during link in sysroot its configured to do so.
>>
>
> Ok, that makes sense. So something like this would be more appropriate?
>
> rel_path = relative_path(mylib, otherlib)
>
> -Wl,-rpath $ORIGIN${relpath}

This could work.

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