We have a set of boards which each run a unique application.
They are loaded by a bootloader which needs to validate the application using a 256 byte header.
The header contains a 64 bit CRC with a proprietary algorithm
We would like to have a common linker command file, which can be customized by
including an application specific header containing a section.
- We need a way to include a linker command file
- It should be possible to specify which directories which contain such included files.
The linker supports adding constant data with the BYTE, SHORT, LONG directives.
- We need 64 bit integers in the same way. Easy to emulate with two LONG, but not so clean
Also does not work when you supply a symbol. - You want to be able to supply a block of ASCII data.with a length
ASCII("My App\n", 16)
ASCIZ("My App", 32);
It is difficult to maintain MEMORY declarations since you have to compute the length.
- The memory directives should support full expressions
- It would be good with an "AFTER function with optional alignment.
I.E:
ROM_start = 0x8000;
HEADER_length = 0x100;
FLASH_end = 0x100000;
MEMORY : {
header : org = ROM_start, len = HEADER_length
app_vectors : org = AFTER(header,0x4), len = VECTOR_length
flash : org = AFTER(app_vectors,0x100), len = FLASH_end - ADDR(flash)
}
Since we need to compute CRC, it would be good with a way to do that in a linker.
- CRC(begin, end, location, size, polynom);
- CRC_ADD(begin, end, location); Allow computation of CRC on multiple segments.
- An alternative to this is to have an application which can read an ELF file
and insert a CRC and update the ELF file..
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We have code space problems. The "_rom_copy_info" table contains entries for ALL segments.
Most of these are NOPs
They have the same source and destination so the "__start" routine will skip the copy.
- _rom_copy_info should not contain 'dud' entries
- The _rom_copy_info table should be listed in the map file.
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The ARM linker contains the "AT" directive allowing the "data" segment to be stored in ROM
and copied to RAM.
I have not found anyway to populate the _rom_copy_info with an entry that actually
does a copy.
If there is a way, it is way to complex.
You need a way to easily specify that a segment is linked to a certain location,
but is placed in another location, with an entry in teh _com_copy_info table.
