Rena <hyperhacker@xxxxxxxxx> writes: > I'm writing patches for a Nintendo 64 game. I can assemble some code > and have the game load and run it, and I've identified several > functions and variables in the existing binary. > > What I want to do now is write my patches in C instead of assembly. I > can easily declare function pointers to use the existing functions, > but I can't find a way to declare variables at a specific address. > Apparently ARM supports an 'at' attribute but that's not implemented > for any other platforms? Otherwise I'll have to use pointers for I can't see any evidence of an 'at' attribute for GCC. There are no ARM specific variable attributes and no 'at' listed in function attributes. https://gcc.gnu.org/onlinedocs/gcc/ARM-Function-Attributes.html#ARM-Function-Attributes How does this feature work and in what tools? > everything (ugly) or define a bunch of variables in the link script > (hard to maintain). > > Is such a feature available for MIPS? I'm not sure if this is possible in a relocatable ELF object for any architecture but there are plenty of unusual features I won't be aware of. I assume you don’t want to do this in a linker script because you don't want to modify the default script? If you have a custom script for this work anyway I'm not sure I understand why it would be harder to maintain a set of symbols in there vs some magic in a C file? You can avoid the need to modify the link script by using linker command line options to define symbols at absolute addresses (--defsym) if that is a better option for you? Hope that helps, Matthew
