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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - llvm-objcopy does not rip off .bss section"
href="https://bugs.llvm.org/show_bug.cgi?id=42277">42277</a>
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<th>Summary</th>
<td>llvm-objcopy does not rip off .bss section
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<th>Product</th>
<td>tools
</td>
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<th>Version</th>
<td>trunk
</td>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>Linux
</td>
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>release blocker
</td>
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<th>Priority</th>
<td>P
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<th>Component</th>
<td>llvm-objcopy/strip
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>masahiroy@kernel.org
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<th>CC</th>
<td>alexander.v.shaposhnikov@gmail.com, jake.h.ehrlich@gmail.com, jh7370.2008@my.bristol.ac.uk, llvm-bugs@lists.llvm.org, rupprecht@google.com
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<pre>objcopy is often used to convert an ELF file into a raw binary.
In my workflow, I build my firmware, covert it into raw binary by the following
command, then burn it into my embedded board.
$ llvm-objcopy -O binary -R .comment --strip-all my-input.elf my-output.bin
This worked fine until LLVM 8,
and in the same way as GNU toolchain objcopy.
If I use the llvm-objcopy from the latest trunk,
it does not work any more.
The first bad commit is:
commit 2b68379b89263178917e3bd37eaf9154078c2965 (HEAD)
Author: Peter Collingbourne <<a href="mailto:peter@pcc.me.uk">peter@pcc.me.uk</a>>
Date: Fri May 24 00:21:46 2019 +0000
llvm-objcopy: Change sectionWithinSegment() to use virtual addresses
instead of file offsets for SHT_NOBITS sections.
Without this, sectionWithinSegment() will return the wrong answer for bss
sections. This doesn't seem to matter now (for non-broken ELF files), but
it will matter with a change that I'm working on.
Differential Revision: <a href="https://reviews.llvm.org/D58426">https://reviews.llvm.org/D58426</a>
git-svn-id: <a href="https://llvm.org/svn/llvm-project/llvm/trunk@361578">https://llvm.org/svn/llvm-project/llvm/trunk@361578</a>
91177308-0d34-0410-b5e6-96231b3b80d8
Since this commit, llvm-objcopy does not drop .bss section.
So, the produced raw binary is bigger than it should be
since it contains the .bss section.
I patched my build script by adding '-R .bss' explcitly.
$ llvm-objcopy -O binary -R .comment --strip-all -R .bss my-input.elf
my-output.bin
However, I do not think this is the right thing to do.
There is no need to load .bss section, nor should it be included in the image.
Moreover, now llvm-objcopy works differently from GNU toolchain objcopy.
Please take a look.
Thanks.</pre>
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