> Why can the linker not deal with function calls more then a 26 bit
>address offset from teh PC?
The B instruction only has a 24-bit displacement field. That stores a number
of words which gives you a 26-bit address offset. To do jumps beyond that,
the linker would have to bounce the call through a PLT entry. It probably
wouldn't be too hard to make this happen automatically for out of range
jumps if you wanted (though this should be controlled by a switch). As a
matter of passing interest modutils already does something a bit like this
so that kernel modules can be quite distant from the main code body.
Another possibility would be to extend the compiler and/or assembler to let
you declare a particular function call as being "long" and have that generate
code that rather than a straightforward branch contained code a bit like this:
mov lr, pc
ldr pc, =target
It would take quite a lot to convince me that the latter was worth including
in GCC, though. The linker thing seems conceptually cleaner - there will be
a performance hit but I doubt it is measurable.
In theory a smart linker could actually perform the second trick too but GNU
ld isn't currently up to it.
(Why do you want to do this in the first place, by the way?)
p.
unsubscribe: body of `unsubscribe linux-arm' to [EMAIL PROTECTED]
