[Date Prev][Date Next] [Thread Prev][Thread Next] [Date Index] [Thread Index]

Re: Why kdelibs4-dev and XFree86 4.3.0 don't play nice together (was: Re: xlibs-pic)



On Tuesday 03 June 2003 23:05, Frank Van Damme wrote:
> ...which brings up the question: wtf is PIC? :)

[P]osition [I]ndependant [C]ode. On x86 it is a little bit slower than
normal code since the data section is accessed using the ebx register
as index. The result is that the compiler has less possibilities to
optimize the code since one general register is reserved. Therefore
there exist two versions of libaries: Static libraries don't need PIC
code since the position (and therefore the position of the data segment)
is know at link time, that is compile time. And shared libraries, which
are linked at runtime and therefore has to be PIC.

Note that it would be possible to use non-PIC code for shared libraries
by simply relocating all symbols accessing data. But that would lead to
patching the code segment which would make it impossible to share the
same library between different address spaces (at least with ELF).

Frank
-- 
## Dept. of Computer Science, Dresden University of Technology, Germany ##
## http://os.inf.tu-dresden.de/~fm3                                     ##

Attachment: pgpqUeNn5Dfab.pgp
Description: signature


Reply to: