I'm using IAR toolchain to compile few source files and then link generated .o files.
However, I'm running into linking errors like below:
Error[Li005]: no definition for "main" [referenced from cmain.o(rt7M_tl.a)]
Error[Lc036]: no block or place matches the
pattern "ro code section .intvec in vector_table_M.o(rt7M_tl.a)"
As I understand, ILINK linker is trying to link object files as an executable image and in the process adding dependencies from standard libraries[ i.e looking for main() and interrupt vector table ].
What I'm looking for :
How to configure linker to not to add these system-library dependencies like main/start/interrupt-vector-table etc. ?
How to configure linker to output a non-executable image from bunch of object files - if that at all is possible ?
You can think of this non-executable image sort of configuration-table image which will be put in persistent memory to be read/write by main application image.
If you tell the linker that you don't have an entry point with the command line option '--no_entry' you will get rid of the reference to main and the .intvec data.
However you do need to tell the linker what it should keep.
--keep and/or __root can help you with that.
Related
I am linking multiple .so files while generating an executable in linux environment. Now what I want is the memory map which shows the memory range for individual .so files linked in executable, something like
0x12345678 - 0x12345800 -> lib1.so
0x12345800 - 0x12345A0C -> lib2.so
0x12345A0C - 0x12346A00 -> lib3.so
For generating the map file I am passing the parameter to gcc linker with "-Wl,-Map=output.map", but the generated map file doesn't show information in this format.
Is it possible to generate map files for .so files like this? If yes then can someone suggest how to generate the map file which contains information like this?
.so files are linked in dynamically at run time - Their load address isn't known at link time, so a map file like you want it cannot be produced.
If you want a static map known at link time, you need to link with static libraries or just live with the fact that it's the OS that decides at run time where the .so libs are loaded.
ldd will show you what external references will be needed to be resolved at load time - But it obviously cannot tell you the addresses.
Is it possible to generate map files for .so files like this?
It is possible to generate a map like this at runtime from within the process, e.g. by examining /proc/self/maps, or following the runtime loader _r_debug->r_map link list.
As tofro's answer correctly states, it is not possible to generate such a map at static link time, because the load address of shared libraries is not known until the binary starts running.
The point is to generate a hex without main function using IAR linker - xlink?
This code should be loaded into the RAM of RL78 MCU.
A quick Google search of iar generate hex from library brought me to this document, "Creating an Absolutely Placed Library", as a first result. It has all the information you need, plus some information on using a CRC for consistency checking. The document is for the IAR EWRX variant, but the concepts should all be the same.
The basic process is to compile your library as an executable, but without a main() function in it. You'll need to set your library configuration under General -> Library Options to None. You can also setup your file conversion settings at this point.
Since you don't have a main() function for a program entry point, you will need to create an entry function to call the IAR C runtime initialization function, __iar_data_init2(), and then set the linker to use this function as the entry point (which can be found under Linker Options -> Library Options).
When building a library, all the symbols will be preserved until the final link step for the application using it, but since you are building this as an executable, it is important that the symbols you want to keep have the __root keyword, or under Linker -> Extra Options you can specify --no-remove to keep all symbols.
In the next step, you need to use isymexport to export the symbols that you want. You will need a file to direct the tool what to export. In the example, they have a file that just contains the following:
show lib_*
show __checksum*
This will direct the tool to export all symbols beginning with lib_ and all symbols beginning with __checksum. They note that __iar_data_init2() should not be exported, as this would cause conflicts with the application that ultimately will use this code. You invoke the tool like so:
isymexport <path to .out file> <path to output from tool> --edit <path to file created above>
Now you should have the output from isymexport and the library file that you were looking for. For the application using this library, you'll need to add the output from isymexport as a library under Linker -> Library, and in your application, you'll need to call your entry function in the library before you attempt to use any of the library's symbols.
This should be the information you need to generate a library that lives in a hex file and can be loaded separately, as well as how to use that library. The referenced document has a lot more detail, so if it is available at that link (or can be found elsewhere by title) it will be a better reference than my summary here.
anyone can help me?? my board is LPC1768 and the sensor is BMP180
Rebuild target 'Target 1'
compiling BMP180.c...
compiling I2C.c...
assembling startup_LPC17xx.s...
compiling system_LPC17xx.c...
compiling GPIO_LPC17xx.c...
compiling PIN_LPC17xx.c...
linking...
.\Objects\asdsa.axf: Error: L6218E: Undefined symbol main (referred from __rtentry2.o).
Not enough information to list image symbols.
Finished: 1 information, 0 warning and 1 error messages.
".\Objects\asdsa.axf" - 1 Error(s), 0 Warning(s).
Target not created.
I found the solution is easy, but before going deeper into the solution, keep in mind that C compilation unit (C Compiler and Assembler at least) compiles each pure C source file after resolving necessary pre-processor directives, and generates a relocatable object file as a result of compilation.
After the compilation unit does its job, there is another unit that is responsible for combining individually every source file that is compiled successfully into the relocatable form of one big object file for all. This unit is called Linker and the operation is called Linking
A very important feature in relocatable object file is that what is called variable, function will be noted as symbol so far. The linker has to solve the symbols, defining what is originally defined in an object file, reference what is being used in another to their original object file.
After this motivation, now we can call main() function as main() symbol.
I Found that the problem is because the source file that contains the main() function was not compiled. As a result, there is no a relocatable object file that contains the symbol corresponding to main() function. Hence, the compiler is complaining: you asked me to use (reference) a symbol you guaranteed to be found (defined) in another file but I found no such symbol!
The solution:
For Kiel IDE, to queue a source file for a compilation; you gotta shortlist it in the category "Source Group",by clicking right, either adding new files to group, or existing files to group. It will result in something like the following figure:
Now we have a main function, is turned (defined) to main symbol later, and found by the linker to reference it to whatever use it in any other relocatable object files.
I solved this problem with the following steps;
Delete your old project and create new project
Choose true library from Manage Run Time Environment like so:
Configure "Options for Target" segment. Define symbol USE_STDPERIPH_DRIVER and define project path like so:
Test your configuration. Please write the following code:
#include "stm32f10x.h" // Device header
int main() {
}
I had the same issue. The problem was that the function name in .c file had a different name with the one in the .h file, and I didn't know.
just add your c file (ex: 'main.c') to the source group (ex: 'source group 1') by expanding the target then right click on the source group, choose add existing files to group 'your source group', then choose the main.c file.
http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.faqs/14222.html
This should help.
Just create a dummy main() or main.c file. Linker can't find it in your pjt.
For solution only add this file C to driver folder and translate it,
Solved: This "Target Not Created" Issue was Resolved by the setting of Run Time Environment as shown in below(url) image.https://i.stack.imgur.com/kJ4IL.jpg ( consisting of CMSIS and Device supporting components in Run time environment)
{ compiling TransformFunctions.c...
linking...
Program Size: Code=768 RO-data=320 RW-data=4 ZI-data=612
FromELF: creating hex file...
".\Objects\LPC1768_B_T.axf" - 0 Error(s), 0 Warning(s).
Build Time Elapsed: 00:00:07
}
I'm pretty new to working with libraries and I'm in the process of trying to understand some specifics regarding static libraries and object files.
Summary
The behavior I'm noticing is that I can link several objects to make an executable with no problem, but if I take an intermediate step of combining those objects into static libraries, I cannot link those static libraries to make an executable without additionally specifying the needed C Run-time library in the link command.
Also, or the record, I'm doing the compiling/linking with Visual Studio 2010 from the command line. More details of the process I'm following are below.
First, let's say I have four source files in a project: main.c, util1.c, util2.c, and util3.c.
What works
I can compile these sources with the following command:cl -c main.c util1.c util2.c util3.cAs a result, I now have four object files: main.obj, util1.obj, util2.obj, and util3.obj. These object files each contain a DEFAULTLIB statement intended to inform the linker that it should additionally check the static C Run-time library libcmt.lib for any unresolved external dependencies in these object files when linking them.
I can create an executable named "app_objs.exe" by linking these objects with the following command:
link -out:app_objs.exe main.obj util1.obj util2.obj util3.obj
As mentioned in step 1, the linker used the runtime library due to the compiler's step of adding a default library statement to the objects.
Where I'm confused
Let's say I want to have an intermediate step of combining these objects into static libraries, and then linking those resulting LIB files to create my executable. First, I can create these libraries with the following commands:
link -lib -out:main.lib main.obj
link -lib -out:util.lib util1.obj util2.obj util3.obj
Now, my original thought was that I could simply link these libraries and have the same executable that I created in step 2 of "What works". I tried the following command and received linker error LNK1561, which states that an entry point needs to be specified:
link -out:app_libs.exe main.lib util.lib
From Microsoft's documentation, it is evident that linking libraries without any object files may require entry points to be specified, so I modified the command to set the subsystem as "console" to specify that the executable in intended to be a console application (which seems to imply certain entry points, thereby resolving that error):link -out:app_libs.exe -subsystem:console main.lib util.libUnfortunately, now I get a linker error stating that mainCRTStartup is an unresolved external symbol. I understand that this is defined in the C runtime library, so I can resolve this issue by manually specifying that I want to link against libcmt.lib, and this gives me a functioning executable:link -out:app_libs.exe -subsystem:console main.lib util.lib libcmt.lib
What I'm not understanding is why the default library info that the compiler placed in each object file couldn't be used to resolve the dependency on libcmt.lib. If I can link object files without explicitly stating I want libcmt.lib, and I created static libraries that are containers for the object files, why can't I link those static libraries without having to explicitly state that I want libcmt.lib? Is this just the way things are, or is there some way I could create the static libraries so that the linker will know to check for unresolved symbols in the runtime library?
Thanks for your help. If I have some fundamentally incorrect ideas here, I'd love suggestions on good references to learn all of this correctly.
Well the answer to your misunderstanding is that .lib files are often a product in themselves, and the compiler can't make those assumptions safely. That's what "external" is for.
If I produce binaries for someone's platform because its users are totally helpless, and they want/need static linkage, I have to give them foo.h and libfoo.lib without tying them to a specific runtime entry point. They may very well have defined their own entry point already for their final product, whether DLL or EXE.
You either want the runtime, or you want your own .obj that contains your entry point. Be warned that declaring and defining mainCRTStartup on your own may mean you're not executing important instructions for the target platform.
I am working with a different compiler CC. It doesn't work like GCC.
When I was using GCC, I can do "gcc -o exe_filename source_filename" and the output would be a exe file.
When I use CC, I need 2 steps. First I compile the source files (suppose it involve a .c and a .h file ) and it create a .lis file and a .obj file. Then I do a link command which created a .exe file.
What is the relationship between LIS, OBJ and EXE files? I ask this because I wonder which files do I need if I want to use the exe in another machine without including unnecessary files. If LIS and OBJ were only used for compilation, I don't need it in another machine.
The compiler takes C files (and includes H files as referenced) and produces object (OBJ) and listing (LIS) files. The object file contains the code and data, but has unresolved external references. The listing typically includes line numbers, error and warning messages, and optional sections such as a type and variable cross-reference.
The linker combines object files and resolves external references to libraries. The result is an executable (EXE) image. (Or shareable image when creating libraries.)
Only the executable file needs to be copied from one system to another to run the application. The listing may be useful for interpreting error messages as it provides the properly correlated line numbers. The object could be useful if the application needs to be relinked due to changes in libraries, particularly if the target system has older versions than the original system.
the OBJ files are the compiled C files in a format that they can be "Linked" together by a linker and turned into an EXE.
Compile -> OBJ -> Link -> EXE
the LIS file is just informational output of the C that the compiler ends up compiling.
All you need once compiled and linked is the EXE
You don't need the other files. The exe will work fine by itself.
I don't have much idea on LIS. But the difference between OBJ and EXE is OBJ file may contain unresolved symbols and in EXE file all symbols are linked and resolved.
If another machine also has same hardware then u can use direct exe to run else you have to cross compile