[CMake] Linking twice for CRC32
Hello everyone,
For integrating the CRC to an ELF I believe I will need to link twice.
First to create a binary on which to caclulate the CRC, and using a
second pass to actually put the CRC into a the symbol at the last part
of the RAM. Using the pointers by Eric Noulard I have constructed the
following CMake code, which links the file, exports a binary BIN file
(the actual ROM image, and then calculates the CRC into a file called
$.crc32.
# Exprimental CRC32 support
add_library(clb_v2_dom.objs OBJECT ${F_GEN} ${F__DOM})
target_compile_definitions(clb_v2_dom.objs PUBLIC -DDOM -DCLBV2 )
add_executable(clb_v2_dom.elf $)
add_custom_command(TARGET clb_v2_dom.elf POST_BUILD
COMMAND ${CMAKE_OBJCOPY} $ ${SECTIONS}
-O binary $.bin
COMMAND ${Python_EXECUTABLE} ${CMAKE_SOURCE_DIR}/tools/crc32.py
$.bin > $.crc32
)
with linker flags defined as
# Bring up the linker
add_link_options(
-nostartfiles
-nodefaultlibs
-Wl,--gc-sections
-nostdlib
-T ${CMAKE_SOURCE_DIR}/${P_SRC}/romram.ld
-Wl,--defsym=CRC_VALUE=0
-Wl,--defsym=_start=0
)
However, the last part is to link the file again with *exactly* the same
invocation as the original linking, except for the
'-Wl,--defsym=CRC_VALUE=<>' instead of 0.
Can anyone give me points on how to achieve this goal?
Kind regards,
Vincent
--
National Institute for Subatomic Physics Nikhef
Department of Computer Technology
Science Park 105
1098 XG AMSTERDAM
tel. : +31 (0)20 592 2032
e-mail: v.van.beve...@nikhef.nl
site : http://www.nikhef.nl/~vincentb
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Re: [CMake] Adding CRC32 to ELF
Hi Eric,
Thanks for your prompt reply.
I have been able to follow your steps up until the item, so thanks!
COMMAND ${CMAKE_C_COMPILER} $
--symbol $.crc32 $
I ran into two challenges:
- The argument '$.crc32' should be the
actual content of the file, and not the file itself, i.e. the calculated
CRC value. How to do this?
- As far as I can see, non of the previously defined linker flags are
added to this command. Of course I can do this, but it would mean I need
to define things twice.
Cheers,
Vincent
On 7-10-2019 at 15:55 wrote Eric Noulard:
Le lun. 7 oct. 2019 à 14:41, Vincent van Beveren
mailto:v.van.beve...@nikhef.nl>> a écrit :
Hello everyone,
I'm setting up a new build targeting an embedded platform (LM32) and
trying to integrate a CRC32 into the resulting ELF. I have previously
done this using plain Makefiles with the following steps (pseudo
code):
target.elf:
link --symbol CRC_VALUE=0 intermediate.elf
objcopy --binary intermediate.elf intermediate.bin
link --symbol CRC_VALUE=`crc32 intermediate.bin`
target.elf
rm intermediate.bin
Now I would like to achieve the same thing with CMake. I'm using
add_executable with multiple targets. The end of my CMakeLists.txt
looks
like this, where F_GEN contains generic source files and F__* source
files specific for that variant of the build:
# [...defining of cross compiler, and source files, some compile
flags,
etc...]
# Educate the linker
add_link_options(
-nostartfiles
-nodefaultlibs
-nostdlib
-Wl,--gc-sections
-T ${CMAKE_SOURCE_DIR}/${P_SRC}/romram.ld
-Wl,--defsym=CRC_VALUE=0
-Wl,--defsym=_start=0
)
# DOM v2 target
add_executable( clb_v2_dom.elf ${F_GEN} ${F__DOM} )
target_compile_definitions(clb_v2_dom.elf PUBLIC -DDOM -DCLBV2 )
# BASE v2 target
add_executable( clb_v2_base.elf ${F_GEN} ${F__BASE} )
# TODO migrate define 'DUBASE' -> 'BASE'
target_compile_definitions(clb_v2_base.elf PUBLIC -DDUBASE -DBASE
-DCLBV2)
# Golden v2 target
add_executable( clb_v2_golden.elf ${F_GEN} ${F__GLD} )
target_compile_definitions( clb_v2_golden.elf PUBLIC -DGOLDEN
-DCLBV2 )
==
As you can see CRC_VALUE is now simply defined 0 for every target.
Which
works well for compiling but during runtime poses a problem to the
ROM
verification procedure. What would a 'proper' way be of adding a
CRC to
an ELF file be using CMake, and be different for each target. Any
help
is welcome!
I would try to add a set of custom command as POST_BUILD event.
https://cmake.org/cmake/help/v3.15/command/add_custom_command.html#build-events
add_custom_command(TARGET clb_v2_base.elf POST_BUILD
COMMAND crc32 $
> $.crc32
COMMAND ${CMAKE_C_COMPILER}
--symbol $.crc32
$
)
I don't know if the linker can read the computed crc32 from the
previously generated file but you get the idea.
Moreover if you want to easily collect objects used for linking a
target you may need to use an intermediate
OBJECT library in order to be able to retrieve $
see:
https://cmake.org/cmake/help/latest/command/add_library.html#object-libraries
i.e. replace:
add_executable( clb_v2_dom.elf ${F_GEN} ${F__DOM} )
by
add_library(clb_v2_dom.objs OBJECT ${F_GEN} ${F__DOM})
add_executable(clb_v2_dom.elf $)
and then:
add_custom_command(TARGET clb_v2_dom.elf POST_BUILD
COMMAND crc32 $
> $.crc32
COMMAND
${CMAKE_C_COMPILER} $
--symbol $.crc32
$
)
If this looks ok to you I would then write my own
lm32_add_executable that would wraps this up in order to be called as:
lm32_add_executable(EXECUTABLE clb_v2_dom.elf
SOURCES ${F_GEN} ${F__DOM})
Kind regards,
Vincent
--
National Institute for Subatomic Physics Nikhef
Department of Computer Technology
Science Park 105
1098 XG AMSTERDAM
tel. : +31 (0)20 592 2032
e-mail: v.van.beve...@nikhef.nl <mailto:v.van.beve...@nikhef.nl>
site : http://www.nikhef.nl/~vincentb
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--
E
[CMake] Adding CRC32 to ELF
Hello everyone,
I'm setting up a new build targeting an embedded platform (LM32) and
trying to integrate a CRC32 into the resulting ELF. I have previously
done this using plain Makefiles with the following steps (pseudo code):
target.elf:
link --symbol CRC_VALUE=0 intermediate.elf
objcopy --binary intermediate.elf intermediate.bin
link --symbol CRC_VALUE=`crc32 intermediate.bin` target.elf
rm intermediate.bin
Now I would like to achieve the same thing with CMake. I'm using
add_executable with multiple targets. The end of my CMakeLists.txt looks
like this, where F_GEN contains generic source files and F__* source
files specific for that variant of the build:
# [...defining of cross compiler, and source files, some compile flags,
etc...]
# Educate the linker
add_link_options(
-nostartfiles
-nodefaultlibs
-nostdlib
-Wl,--gc-sections
-T ${CMAKE_SOURCE_DIR}/${P_SRC}/romram.ld
-Wl,--defsym=CRC_VALUE=0
-Wl,--defsym=_start=0
)
# DOM v2 target
add_executable( clb_v2_dom.elf ${F_GEN} ${F__DOM} )
target_compile_definitions(clb_v2_dom.elf PUBLIC -DDOM -DCLBV2 )
# BASE v2 target
add_executable( clb_v2_base.elf ${F_GEN} ${F__BASE} )
# TODO migrate define 'DUBASE' -> 'BASE'
target_compile_definitions(clb_v2_base.elf PUBLIC -DDUBASE -DBASE -DCLBV2)
# Golden v2 target
add_executable( clb_v2_golden.elf ${F_GEN} ${F__GLD} )
target_compile_definitions( clb_v2_golden.elf PUBLIC -DGOLDEN -DCLBV2 )
==
As you can see CRC_VALUE is now simply defined 0 for every target. Which
works well for compiling but during runtime poses a problem to the ROM
verification procedure. What would a 'proper' way be of adding a CRC to
an ELF file be using CMake, and be different for each target. Any help
is welcome!
Kind regards,
Vincent
--
National Institute for Subatomic Physics Nikhef
Department of Computer Technology
Science Park 105
1098 XG AMSTERDAM
tel. : +31 (0)20 592 2032
e-mail: v.van.beve...@nikhef.nl
site : http://www.nikhef.nl/~vincentb
--
Powered by www.kitware.com
Please keep messages on-topic and check the CMake FAQ at:
http://www.cmake.org/Wiki/CMake_FAQ
Kitware offers various services to support the CMake community. For more
information on each offering, please visit:
CMake Support: http://cmake.org/cmake/help/support.html
CMake Consulting: http://cmake.org/cmake/help/consulting.html
CMake Training Courses: http://cmake.org/cmake/help/training.html
Visit other Kitware open-source projects at
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Follow this link to subscribe/unsubscribe:
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