--change-section address and its alias --adjust-section-vma allows
modification
of section addresses in a relocatable file. This used to be used, for
example,
in Fiasco microkernel.
On a relocatable file this option behaves the same as GNU objcopy, apart
from
the fact that it does not issue any warnings, for example, when an
argument is
not used.
GNU objcopy does not produce an error when passed an executable file but
the
usecase for this is not clear, and the behaviour is inconsistent. The
idea of
GNU objcopy --change-section-address is that the option should change
both LMA
and VMA in an executable file. Since this patch does not implement
executable
file support, only VMA is changed.
llvm-objcopy did not support change-section-lma argument.
This patch adds support for a use case of change-section-lma, that is
shifting load address of all sections by the same offset. This seems to
be the only practical use case of change-section-lma, found in other
software such as Zephyr RTOS's build system.
This is an option that could possibly be supported in some other than
ELF formats, however this change only implements it for ELF. When used
with other formats an error message is raised.
In comparison, the behavior of GNU objcopy is inconsistent. For some ELF
files it behaves the same as described above. For others, it copies the
file without modifying the p_paddr fields when it would be expected. In
some experiments it modifies arbitrary fields in section or program
headers. It is unclear what exactly determines this.
The executable file generated by yaml2obj in this test is not parsable
by GNU objcopy. With Machine set to EM_AARCH64, the file can be parsed
and the first test in the test file completes with 0 exit code. However,
the result is rather arbitrary. AArch64 GNU objcopy subtracts 0x1000
from p_filesz and p_memsz of the first LOAD section and 0x1000 from
p_offset of the second LOAD section. It does not look meaningful.
Add --skip-symbol and --skip-symbols options that allow to skip symbols
when executing other options that can change the symbol's name, binding
or visibility, similar to an existing option --keep-symbol that keeps a
symbol from being removed by other options.
`--gap-fill <value>` fills the gaps between sections with a specified
8-bit value, instead of zero.
`--pad-to <address>` pads the output binary up to the specified load
address, using the 8-bit value from `--gap-fill` or zero.
These options are only supported for ELF input and binary output.
Add support for --dump-section on COFF files. This is helpful for
extracting specific content from an object file on Windows.
Differential Revision: https://reviews.llvm.org/D150305
Reviewed By: @alexander-shaposhnikov, @jhenderson, @hjyamauchi
The request is mentioned on D129053. I feel that having this functionality is
mildly useful (not strong).
* Rename .ctors to .init_array and change sh_type to SHT_INIT_ARRAY (GNU objcopy
detects the special name but we don't).
* Craft tests for a new SHT_LLVM_* extension
Reviewed By: jhenderson
Differential Revision: https://reviews.llvm.org/D129337
Summary: This is an initial implementation of lvm-objcopy for XCOFF32.
Currently only supports simple copying, op-passthrough to follow.
Reviewed By: jhenderson, shchenz
Differential Revision: https://reviews.llvm.org/D97656
