objdump -S for a different dir.

objdump -S for a different dir.

[Jim Cromie]

hi folks,

out of habit, I build my kernels to a build tree
ie use make O=../build-foo just once,
then cd ../build-foo, and thereafter run make there

this doesnt play nice with objdump -S
--source
           Display source code intermixed with disassembly, if
possible.  Implies -d.

it seems its not possible unless the source and obj are in the same file.
GDB manages to find the source, whats missing in objdump ?

FWIW, Id love a micro-tutorial on this,
anyone know how to display, dissect the obj file, debuginfo etc ?
or can recommend some on-line tome that gets into it at some breadth and depth ?
many many search hits are for quick Q&A that doesnt get deeper than a puddle.

thanks

objdump -S for a different dir.

[Dave Hylands]

Hi Jim,

On Fri, Dec 9, 2011 at 10:59 PM, Jim Cromie <jim.cromie@gmail.com> wrote:

> hi folks,
>
> out of habit, I build my kernels to a build tree
> ie use make O=../build-foo just once,
> then cd ../build-foo, and thereafter run make there
>
> this doesnt play nice with objdump -S
> --source
>           Display source code intermixed with disassembly, if
> possible.  Implies -d.
>
> it seems its not possible unless the source and obj are in the same file.
> GDB manages to find the source, whats missing in objdump ?
>
> FWIW, Id love a micro-tutorial on this,
> anyone know how to display, dissect the obj file, debuginfo etc ?
> or can recommend some on-line tome that gets into it at some breadth and
> depth ?
> many many search hits are for quick Q&A that doesnt get deeper than a
> puddle.
>

So I normally do out of tree builds, but I always run make from the source
tree and specify the O= option.

I'm using 3.0.1, and in menuconfig, I went into "Kernel hacking", enabled
"Kernel debugging" and then "Compile the kernel with debug info".

The "Compile the kernel with debug info" option enables CONFIG_DEBUG_INFO
which cause the kernel source to be compiled with the -g option which adds
the debugging information needed to find the source from the objects.

I normally cross compile for the ARM, so I then cd'd into my build tree and
tried arm-linux-gnueabi-objdump -S on a few object files and they all gave
intermingled C and assembler listings.

I tried it using your method and it seemed to work fine for me as well.

-- 
Dave Hylands
Shuswap, BC, Canada
http://www.davehylands.com
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.kernelnewbies.org/pipermail/kernelnewbies/attachments/20111209/8a76be69/attachment.html 

objdump -S for a different dir.

[Jim Cromie]

On Sat, Dec 10, 2011 at 12:46 AM, Dave Hylands <dhylands@gmail.com> wrote:
> Hi Jim,
>
> On Fri, Dec 9, 2011 at 10:59 PM, Jim Cromie <jim.cromie@gmail.com> wrote:
>>
>> hi folks,
>>
>> out of habit, I build my kernels to a build tree
>> ie use make O=../build-foo just once,
>> then cd ../build-foo, and thereafter run make there
>>
>> this doesnt play nice with objdump -S
>> --source
>> ? ? ? ? ? Display source code intermixed with disassembly, if
>> possible. ?Implies -d.
>>
>> it seems its not possible unless the source and obj are in the same file.
>> GDB manages to find the source, whats missing in objdump ?
>>
>> FWIW, Id love a micro-tutorial on this,
>> anyone know how to display, dissect the obj file, debuginfo etc ?
>> or can recommend some on-line tome that gets into it at some breadth and
>> depth ?
>> many many search hits are for quick Q&A that doesnt get deeper than a
>> puddle.
>
>
> So I normally do out of tree builds, but I always run make from the source
> tree and specify the O= option.
>
> I'm using 3.0.1, and in menuconfig, I went into "Kernel hacking", enabled
> "Kernel debugging" and then "Compile the kernel with debug info".
>
> The "Compile the kernel with debug info" option enables CONFIG_DEBUG_INFO
> which cause the kernel source to be compiled with the -g option which adds
> the debugging information needed to find the source from the objects.
>
> I normally cross compile for the ARM, so I then cd'd into my build tree and
> tried arm-linux-gnueabi-objdump -S on a few object files and they all gave
> intermingled C and assembler listings.
>
> I tried it using your method and it seemed to work fine for me as well.
>
> --
> Dave Hylands
> Shuswap, BC, Canada
> http://www.davehylands.com


Thanks Dave,

Id have sworn that after I found -S to not work out-of-tree,
I built in-tree using same .config and -S did work.
But of course that in-tree build is gone and I cant verify.
(it interferes with continued out-of-tree builds, which end with 'run
make mrproper')

Anyway, its certainly working now.
It was probably a different config on a different box, built for a small CF.

thanks again