Date: Tue, 1 Apr 1997 09:31:02 +0100 (BST) From: Doug Rabson <dfr@nlsystems.com> To: John Polstra <jdp@polstra.com> Cc: phk@critter.dk.tfs.com, current@FreeBSD.ORG Subject: Re: A new Kernel Module System Message-ID: <Pine.BSF.3.95q.970401092941.305A-100000@kipper.nlsystems.com> In-Reply-To: <199704010326.TAA24955@austin.polstra.com>
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On Mon, 31 Mar 1997, John Polstra wrote: > On a different but related subject ... Maybe nobody's confused about > this, but just in case: The kernel modules (new LKMs) do not have > to be PIC. They can just as well be plain object files, and they > probably should be. PIC is only needed when the same object is > going to be mapped simultaneously into several different processes > at potentially different addresses. PIC doesn't eliminate the need > for relocation; it just isolates all the position-dependent > information in the data segment. Since each kernel module will be > mapped at most once into the kernel, there's no need to make it PIC. > It should probably not be PIC, because of the substantial > performance penalty that PIC adds. Exactly what I was thinking. PIC has no benefits for the kernel. The only thing I would need from the a.out shlib format is the relocations and runtime symbol table. -- Doug Rabson Mail: dfr@nlsystems.com Nonlinear Systems Ltd. Phone: +44 181 951 1891
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