[lldb-dev] LLDB failed to locate source when dwarf symbols are inside compile unit on Linux

[Greg Clayton via lldb-dev]

In ELF files if there is a section named “.gnu_debuglink” it will contain a path to the external debug file. Dump this section and see what it contains. This section contains a null terminated C string as the path followed by a 4 byte aligned 32 bit integer which is a file CRC. Check to see the path is relative.

I am guessing this is your problem.

Greg


> On Jan 9, 2017, at 3:42 PM, Jeffrey Tan <jeffrey.fudan at gmail.com> wrote:
> 
> Hey Greg, I just confirmed this with our build team. I seem to have misunderstood the location of debug symbol. It is actually not inside each individual object file but:
> The debug info in dev mode sits in the .debug_* sections of the shared libraries (we don't use debug fission).
> One potential complicating factor is that we relativize the DW_AT_comp_dirattributes in the DWARF info, so that it's almost always just a long reference to the current working directory (e.g. .///).
> 
> I do not know why this(symbol in shared library) would cause the bug though.
> 
> Jeffrey
> 
> On Mon, Jan 9, 2017 at 1:57 PM, Greg Clayton <clayborg at gmail.com <mailto:clayborg at gmail.com>> wrote:
> Comments below.
> 
>> On Jan 9, 2017, at 1:10 PM, Jeffrey Tan via lldb-dev <lldb-dev at lists.llvm.org <mailto:lldb-dev at lists.llvm.org>> wrote:
>> 
>> Hi,
>> 
>> O ur company is using Buck(https://buckbuild.com/ <https://buckbuild.com/>) to build internal service. Recently the build team made a change in buck to not merge dwarf symbols from each object file into final binary so debugger needs to read source/symbol table from compilation unit itself.
> 
> How are debug symbols expected to be found? Is fission being used where the DWARF for each compile unit is in .dwo files and the main executable has skeleton DWARF? I will skip all other questions until we know more about how and where the DWARF is.
> 
> Greg Clayton
> 
> 

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