Re: Prerelease of 2.1.0

Tom May (ftom@netcom.com)
24 Sep 1996 12:23:46 -0700


Uwe Bonnes <bon@elektron.ikp.physik.th-darmstadt.de> writes:

> But dosen't that free up an register for user usage. With ELF, we lost this
> register (giving a lot of programming freedom), could we get it back now?

No, because:

1. This is a kernel, not a user, change.

2. We have freed a segment register, not a general purpose register.

3. ELF uses an additional dedicated register only in position independent
(i.e., shared library) code, and only in functions that access global
variables. And *that* is just a suboptimal implementation of position
independent code which could be fixed.

Note that using ELF does *not* make the kernel code less optimal than
the a.out format because it is not position independent.

Tom.