Hi Pali, Hi Richard,
Interesting... Another test case which is working fine:
kernoffs:
.word 0x40000 - (. - 0x0)
This works because this expression can be converted into an instruction
and a relocation in the object file:
% as t.s -o t.o
% objdump -dr t.o
Disassembly of section .text:
00000000 <kernoffs>:
0: 0003fffc .word 0x0003fffc
0: R_ARM_REL32 *ABS*
Which shows that when this object file is linked the word at offset 0
inside the .text section should be converted into an absolute value of
(pc - 0x4000), where pc is the address of the word.
This instruction however:
.word - (. - 0x80008000)
Cannot be converted since the linker would need to compute ((pc - 0x800800) *
-1)
which cannot be expressed by a single relocation. Similarly:
.word KERNEL_OFFSET - (. - CONFIG_SYS_TEXT_BASE)
Cannot be expressed by a single value, modified by a single relocation, even
when the KERNEL_OFFSET and CONFIG_SYS_TEXT_BASE values are known at assembly
time.
A clever assembler might be able to rearrange the expression, assuming that
overflow is unimportant, but gas does not do that. But just for reference
the following would work:
.word KERNEL_OFFSET + CONFIG_SYS_TEXT_BASE - .
I agree however that this message:
t.s: Error: attempt to get value of unresolved symbol `L0'
is unhelpful. So I am going to check in a patch to change it to:
t.s: Error: expression is too complex to be resolved
I looked into providing a file name and line number with the error
message, but this would involve reworking a lot of the assembler's
internal expression parser.
Cheers
Nick
