Re: Absolute Addressing and asm
Re: Absolute Addressing and asm
- Subject: Re: Absolute Addressing and asm
- From: Terry Lambert <email@hidden>
- Date: Sat, 8 May 2010 00:24:07 -0700
On May 7, 2010, at 1:24 PM, Duane Murphy wrote:
We are adding some assembly optimizations to our code. We are running
into a problem with text relocations. I'm looking for suggestions for
articles or information on how to go about fixing this problem.
The linker returns:
ld: absolute addressing (perhaps -mdynamic_no_pic) used in (some
function) from (path to some library) not allowed in slidable image.
Use '--read_only_relocs suppress' to enable text relocs
The function and file identified in the library are part of our
assembly optimizations.
This happens when linking a library built with the assembly code into
a framework (aka dylib).
Looking at the code, the problem stems from access to an external
table. The table is compiled in a .c file. The assembler has no
(automatic) way of constructing a relative address to that table. This
apparently leaves the linker to work out what the address is, which
leaves the assembly in a state where it wants an absolute address.
(Yes, some of this is guessing, which is why I am asking. :-)
I am also working towards using this same code in a kext which, I
expect, will have similar issues.
Can anyone recommend reading or suggestions for how to resolve this
situation?
Write C code to reference the table and do a gcc -S on it and look at
how the compiler writes its assembly to reference it, and write your
assembly the same way.
FWIW: You are probably trying to hard here, and would be better off
writing C code and using the ASM() directive to embed assembly.
-- Terry
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