Hi,
I am trying to create a binary image that can be run from either 0x08010000 of 0x08044000 in a STM32L476 Processor using the Keil MDK-ARM 5.42.0.0 Development environment with the armclang 6.23/6.19/5.06 (Options I have tried) compiler.
I am unable to find detailed documention on how to make this work.
I have found a trivial project guidelines that does not really include any of the sections needed in the scatter file.
here is the trivial example: https://developer.arm.com/documentation/100748/0624/Mapping-Code-and-Data-to-the-Target/Bare-metal-Position-Independent-Executables?lang=en
However, this is not detailed at all and does not describe what is and what is not supported in Compiler 6.23/6.19/5.06
Here is what I have tried with 6.23:
C/C++(AC6) flags: -fbare-metal-pie,
Asm flags: -fbare-metal-pie <--- argument ununsed during compilation
Linker flags: --bare_metal_pie.
When I do this, I see the following linker warnings/errors:
linking...
.\OBJ\ELSA-16T_Application.axf: Warning: L6083W: Use of the --scatter option with the --pie option is experimental
.\OBJ\ELSA-16T_Application.axf: Warning: L6320W: Ignoring --keep command. Cannot find argument '__arm_relocate_pie_'.
.\OBJ\ELSA-16T_Application.axf: Error: L6218E: Undefined symbol __RW_BASE (referred from startup_stm32l476xx.o).
.\OBJ\ELSA-16T_Application.axf: Error: L6218E: Undefined symbol __arm_relocate_pie_ (referred from anon$$obj.o).
Not enough information to list image symbols.
Not enough information to list load addresses in the image map.
The first warning I am sure was put in for a reason. Use of the --scatter option with the --pie option is experimental. i.e. Your on your own.
The undefined symbol __RW_BASE comes from the startup_stm32l476xx.s where I do this:
IMPORT __RW_BASE
LDR R9, =__RW_BASE
Just before LDR RO, =__main.
The simple scatter file shown in the example link above does not explain how to put __arm_relocate_pie_ into a scatter file.
The next option I tried was also with Compiler 6.23
C/C++(AC6) flags: -fropi -frwpi
Asm flags: -fropi -frwpi
Linker flags: --ropi --rwpi
I have the linker flags with and without --ropi --rwpi.
The only difference is if I get the warnings about --ropi and --rwpi.
linking...
.\OBJ\XXXXX.axf: Warning: L6914W: option ropi ignored when using --scatter.
.\OBJ\XXXXX.axf: Warning: L6914W: option rwpi ignored when using --scatter.
.\OBJ\XXXXX.axf: Error: L6640E: PDTTable section not least static data address, least static data section is .cmis_i2c_table0
Not enough information to list image symbols.
Finished: 1 information, 2 warning and 1 error messages.
".\OBJ\XXXXX.axf" - 1 Error(s), 64 Warning(s).
I have tried adding an attached pdt_marker.c to get the .r9base sections.
With or without the pdt_marker in my scatter file I still get the dreaded error L6640E:
linking...
.\OBJ\XXXXX.axf: Error: L6640E: PDTTable section not least static data address, least static data section is .cmis_i2c_table0
Not enough information to list image symbols.
Finished: 1 information, 0 warning and 1 error messages.
".\OBJ\XXXXX.axf" - 1 Error(s), 62 Warning(s).
Target not created.
I also tried the same strategies on the armclang version 6.11 and 5.06 with similar results using slightly different arguments.
What I would really like is some advice on the best way to make a position independent executable that relocates its vectors to a spot in ram. I have the relocation of the vectors in ram working, I just cannot for the life of me figure out how to get this compiler to use the R9 base ( register R9 ) to make relative jumps and addresses.
Detailed documentation would also be greatly appreciated.
Thanks in advance for any help.
Adrian
