PRC wrote: > I'm studying the ELF specfication version 1.1 recently. I'm confused about the 'addend' which is used in relocation. There doesn't seems to be explict descriptions about 'addend' in the specification. Can somebody make detailed explainations about how to calculate the value of the 'addend' when relocating an executable. It looks like you're only looking at the generic ABI spec. You need to also look at the processor-specific suppliment for whatever platform you're interested in (psABI). In it, the relocation types for that specific architecture will be defined, each with its own formula that may or may not include the addend. For example look at figure 4-4 of the i386 psABI: Name Value Field Calculation ------------------------------------------- R_386_NONE 0 none none R_386_32 1 word32 S + A R_386_PC32 2 word32 S + A - P R_386_GOT32 3 word32 G + A - P R_386_PLT32 4 word32 L + A - P R_386_COPY 5 none none R_386_GLOB_DAT 6 word32 S R_386_JMP_SLOT 7 word32 S R_386_RELATIVE 8 word32 B + A R_386_GOTOFF 9 word32 S + A - GOT R_386_GOTPC 10 word32 GOT + A - P (A is the addend value) Each architecture defines its own set of R_<arch> relocations, each with its own definition, so you can't really deduce anything from the generic spec. Brian
