objcopy --extract-symbol option keeping bogus sections/segments : wrong?

[Vincent Rubiolo]

Hi gentle binutils maintainers,

I am writing to you about the newly added --extract-symbol of objcopy 
(cf [1]) which, as Richard explained, we use to extract symbol files 
from VxWorks kernels.

My concern is about the fact that the option zeroes out the 
addresses/sizes, etc of the sections and segments in the file _instead_ 
of only keeping the relevant bits in. In some circumstances, this 
confuses our kernel loader (which is used to load that stripped file) 
since the segments within the file are marked as loadable but are of 
empty size/address.

I have looked at the ELF spec [2] and while the standard says the image 
can have supplementary segments/sections, it does not specify whether 
they can be empty/marked PT_LOAD.

To me, there is no reason to have these bogus sections/segments in the 
image and they should be removed. I think we should fix the file and not 
the loader itself.

Is this a correct reasoning?

Thanks for your insight.

Vincent

PS: attaching readelf output on VxWorks symbol files

[1] http://sourceware.org/ml/binutils/2007-03/msg00004.html
[2] http://www.sco.com/developers/gabi/latest/contents.html


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