[yocto] Debugging shared libraries
Khem Raj
raj.khem at gmail.com
Thu Feb 11 19:18:55 PST 2016
> On Feb 11, 2016, at 7:11 PM, Gary Thomas <gary at mlbassoc.com> wrote:
>
> On 2016-02-11 22:48, Mark Hatle wrote:
>> On 2/10/16 9:41 PM, Gary Thomas wrote:
>>> On 2016-02-10 21:08, Khem Raj wrote:
>>>>
>>>>> On Feb 10, 2016, at 8:35 AM, Mark Hatle <mark.hatle at windriver.com> wrote:
>>>>>
>>>>> On 2/10/16 1:31 AM, Gary Thomas wrote:
>>>>>> I'm trying to debug some code (mplayer) which uses some shared
>>>>>> libraries from ffmpeg. When I use GDB (via gdbserver), I don't
>>>>>> get all the debug information I need - note that many of the shared
>>>>>> libraries do not have any symbolic debugging info:
>>>>>
>>>>> Is your system using the the split debug binaries, and if so, do you have them
>>>>> all installed on the system that GDB is running on?
>>>>>
>>>>> (When GDB starts, you should see it load the symbols, or error it can't find them.)
>>>>>
>>>>> Assuming you DO have the symbol files available, and some things are lacking
>>>>> debuginfo, it's possible those recipes are not properly building with full
>>>>> symbols (they should be, the whole system should be.)
>>>>>
>>>>> Easiest way to check is do a readelf/objdump on the .debug version of the
>>>>> library and check that there are dwarf symbols present... if not, it's probably
>>>>> a recipe error.
>>>>>
>>>>> --Mark
>>>>>
>>>>>> (gdb) info sharedlibrary
>>>>>> From To Syms Read Shared Object Library
>>>>>> 0xb6fcf800 0xb6feaf08 Yes /tmp/p0382.img/lib/ld-linux-armhf.so.3
>>>>>> 0xb6fa6fa8 0xb6fb2b40 Yes (*) /tmp/p0382.img/lib/libtinfo.so.5
>>>>>> 0xb6f6d210 0xb6f8c200 Yes /tmp/p0382.img/usr/lib/libpng16.so.16
>>>>>> 0xb6f488e8 0xb6f54a60 Yes /tmp/p0382.img/lib/libz.so.1
>>>>>> 0xb6f069f0 0xb6f34264 Yes /tmp/p0382.img/usr/lib/libjpeg.so.8
>>>>>> 0xb6edbaf0 0xb6eee29c Yes /tmp/p0382.img/usr/lib/libdvdread.so.4
>>>>>> 0xb6eb6108 0xb6ec7ae8 Yes /tmp/p0382.img/usr/lib/libass.so.4
>>>>>> 0xb6e808b8 0xb6e95384 Yes /tmp/p0382.img/usr/lib/libvorbis.so.0
>>>>>> 0xb6e6b4b4 0xb6e6d7e4 Yes /tmp/p0382.img/usr/lib/libogg.so.0
>>>>>> 0xb6e48978 0xb6e55eb4 Yes /tmp/p0382.img/usr/lib/libspeex.so.1
>>>>>> 0xb6dfe818 0xb6e1b8b4 Yes (*) /tmp/p0382.img/usr/lib/libfaad.so.2
>>>>>> 0xb6d92df0 0xb6dd4e78 Yes (*) /tmp/p0382.img/usr/lib/libavutil.so.54
>>>>>> 0xb5de0640 0xb64a2e18 Yes (*) /tmp/p0382.img/usr/lib/libavcodec.so.56
>>>>>> 0xb5c17528 0xb5d65840 Yes (*) /tmp/p0382.img/usr/lib/libavformat.so.56
>>>>>> 0xb5b81688 0xb5be8db8 Yes (*) /tmp/p0382.img/usr/lib/libswscale.so.3
>>>>>> 0xb5b5f578 0xb5b6c718 Yes (*) /tmp/p0382.img/usr/lib/libswresample.so.1
>>>>>> 0xb5b44998 0xb5b4b490 Yes (*) /tmp/p0382.img/usr/lib/libpostproc.so.53
>>>>>> 0xb5b1f0e0 0xb5b2e194 Yes /tmp/p0382.img/lib/libpthread.so.0
>>>>>> 0xb5aa4c00 0xb5ad46d0 Yes /tmp/p0382.img/lib/libm.so.6
>>>>>> 0xb5a859ec 0xb5a8fc34 Yes /tmp/p0382.img/usr/lib/libXext.so.6
>>>>>> 0xb597b728 0xb59f92bc Yes /tmp/p0382.img/usr/lib/libX11.so.6
>>>>>> 0xb5946fc8 0xb59573d0 Yes /tmp/p0382.img/usr/lib/libtheoradec.so.1
>>>>>> 0xb5887910 0xb591bbb8 Yes (*) /tmp/p0382.img/usr/lib/libasound.so.2
>>>>>> 0xb58579f8 0xb58586ac Yes /tmp/p0382.img/usr/lib/libXss.so.1
>>>>>> 0xb5844ca0 0xb5846bac Yes /tmp/p0382.img/usr/lib/libXv.so.1
>>>>>> 0xb57e7700 0xb58265e0 Yes /tmp/p0382.img/usr/lib/libSDL-1.2.so.0
>>>>>> 0xb56bae00 0xb57abb28 Yes /tmp/p0382.img/lib/libc.so.6
>>>>>> 0xb569292c 0xb5693724 Yes /tmp/p0382.img/lib/libdl.so.2
>>>>>> 0xb5650a70 0xb566e6a4 Yes /tmp/p0382.img/usr/lib/libfontconfig.so.1
>>>>>> 0xb561e324 0xb563951c Yes /tmp/p0382.img/usr/lib/libexpat.so.1
>>>>>> 0xb559d36c 0xb55f5cb4 Yes /tmp/p0382.img/usr/lib/libfreetype.so.6
>>>>>> 0xb55622b0 0xb5567e84 Yes /tmp/p0382.img/usr/lib/libenca.so.0
>>>>>> 0xb541fbc0 0xb54b5a08 Yes (*) /tmp/p0382.img/usr/lib/libx264.so.144
>>>>>> 0xb53d4df0 0xb53fa0b0 Yes /tmp/p0382.img/usr/lib/libtheoraenc.so.1
>>>>>> 0xb53a72b0 0xb53bd258 Yes (*) /tmp/p0382.img/usr/lib/liblzma.so.5
>>>>>> 0xb5386050 0xb5392cc0 Yes (*) /tmp/p0382.img/usr/lib/libbz2.so.0
>>>>>> 0xb5367810 0xb5373b30 Yes /tmp/p0382.img/usr/lib/libxcb.so.1
>>>>>> 0xb534da00 0xb534e5a8 Yes /tmp/p0382.img/usr/lib/libXau.so.6
>>>>>> 0xb5339f80 0xb533b69c Yes /tmp/p0382.img/usr/lib/libXdmcp.so.6
>>>>>> 0xb5323720 0xb5326ea0 Yes /tmp/p0382.img/lib/librt.so.1
>>>>>> 0xb530b6e0 0xb5311234 Yes /tmp/p0382.img/usr/lib/libXrandr.so.2
>>>>>> 0xb52f3530 0xb52f9060 Yes /tmp/p0382.img/usr/lib/libXrender.so.1
>>>>>> 0xb52d3160 0xb52e18a4 Yes /tmp/p0382.img/lib/libgcc_s.so.1
>>>>>> (*): Shared library is missing debugging information.
>>>>>>
>>>>>> Is this a function of how those libraries were built (by the recipe)
>>>>>> or something else? How can I get the symbolic debugging info enabled?
>>>>>>
>>>>>> Thanks for any pointers
>>>>
>>>>
>>>> Usually it works well if you add
>>>>
>>>> EXTRA_IMAGE_FEATURES_append = “ dbg-pkgs”
>>>>
>>>> image size grows but you get good debug view on target.
>>>>
>>>> another option, I usually use is setup feeds
>>>> and then
>>>>
>>>> opkg install <package>-dbg
>>>>
>>>> which pulls in a section of debug info needed to debug a given package.
>>>>
>>>
>>> I've done all this already. The problem is that for the libraries which
>>> have no symbols there are no corresponding -dbg packages :-( I looked
>>> at the ffmpeg recipe (where the libswresample library I'm most interested
>>> in comes from) and there is serious magic involved in the packaging. I'm
>>> pretty sure that's where the discrepancy lies... Any help understanding
>>> how to fix that would be appreciated.
>>
>> If the package is being built from source, I'd expect -dbg to be generated.. if
>> it's not, we definitely should investigate.
>
> Definitely standard (OE-core) package, being built from sources. No -dbg for
> the libraries in question.
>
>>
>> The intention has always been to generate -dbg for the core pieces.. External
>> layers can disable it if they're packaging binaries or commercial, but that is
>> different.
>
> https://bugzilla.yoctoproject.org/show_bug.cgi?id=9104
>
> As obvious from the list above, there are other packages with libraries that
> have no -dbg as well. This bug was filed against ffmpeg only, perhaps it should
> be more generic…
Can you check if the makery of this package is not respecting the CFLAGS passed from
OE env ?
>
> --
> ------------------------------------------------------------
> Gary Thomas | Consulting for the
> MLB Associates | Embedded world
> ------------------------------------------------------------
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