On 08/05/16 00:56, Irfan Ahmad wrote:
1. In the absence of lazy binding (that is almost always the case in embedded systems), GOT is practically read-only - it needs to be modified only during
'practically' as in 'almost', or is it really read only?
linking by the dynamic linker, after that it can be considered and marked read-only (e.g. read-only attribute set to be enforced by some MMU or MPU).
True, but I don't see how that's related to the -mNPDITR flag. (Your statement is about lazy binding).
2. If you only need a simple dynamic object model - where you just need dynamic loading and dynamic linking - but do not need to maintain multiple data states for the object like you need in a traditional shared object model, then one instance of GOT per dynamic object is enough.
Again, correct, but unrelated to the flag. You seem to be claiming that unix-like ABIS require more than one GOT per dynamic object?
From #1: GOT is read-only so keeping it with CODE segment is a natural choice. Now as there is no need to move it to RAM so there is no need for a mechanism (-mSPB) that would enable controlling the GOT location independently of CODE segment.
That's correct, but again unrelated to the -mNPDITR flag.
2. If you only need a simple dynamic object model - where you just need dynamic loading and dynamic linking - but do not need to maintain multiple data states for the object like you need in a traditional shared object model, then one instance of GOT per dynamic object is enough.
What 'multiple data states?' Are you talking about lazy binfing again (unrelated to -mNPDITR), or something else (what?)
So when both #1 and #2 are met, you only need -mno-pic-data-is-text-relative.
Your conclusion doesn't follow. You can satisfy them with regular GOT behavior. nathan
