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Newsgroups: comp.os.386bsd.development Path: sserve!newshost.anu.edu.au!munnari.oz.au!news.Hawaii.Edu!ames!haven.umd.edu!uunet!news.univie.ac.at!cosy.sbg.ac.at!news From: peter@wiesel (Peter Burgstaller) Subject: Re: Shared libraries and 386bsd. Message-ID: <C4DwDA.HvM@cosy.sbg.ac.at> Sender: news@cosy.sbg.ac.at Nntp-Posting-Host: wiesel Organization: University of Salzburg / Austria References: <1onp3o$l3v@umd5.umd.edu> Date: Wed, 24 Mar 1993 08:17:34 GMT Lines: 59 In article <1onp3o$l3v@umd5.umd.edu> mark@elea.umd.edu (Mark Sienkiewicz) writes: > In article <MCKIM.93Mar23082603@dinah.lerc.nasa.gov> mckim@dinah.lerc.nasa.gov (Jim McKim) writes: > > > >There is partial support in gcc for pic code. > >Some enhancements will have to be made to the assembler. > > > >One additional caveat - it looks like gcc sacrifices the ebx register > >to the cause when pic is used. The 386 architecture isn't real good at > >supporting pic operations. Since it doesn't have that many registers, > >I wonder what the effect on performance is. > > There's another spooky possibility... > > The 386 has segment registers. > > (go ahead -- flame away :) > > If you placed each shared library in it's own segment, you could link the > library based at 0 and avoid some of the PIC problems. You pay for it > by dealing with the segmentation stuff. > > If you give each library it's own code segment, it doesn't need to be position > independent code. You still need to handle data. > > If you give each library it's own data segment, you don't need to handle > position independent data, but you _do_ need to worry about which segment > pointers point into, etc. If you write your library to use only local > variables and dynamically allocated memory, you don't even need to have > a data segment for it. > > (We have all this brain-damaged segmenting stuff hanging around anyway... maybe > we can use it for something.) > > Mark S. I'm sorry but I don't know much about the internals and stuff, BUT the only thing I can say to this is: It would be a GREAT enhancement for 386BSD if we'd have shared libs and shared memory. Not everybody is in the lucky position to have a 200MB or 300MB harddisk to run the system and keep up with upgrades, patches ... - Correct me if I'm wrong! - Peter -- /--------------------------------------------------------\ | Peter Burgstaller| Student of Computerscience | | (peter@cosy.sbg.ac.at)| in Salzburg, Austria (Europe) | | "So Long, and Thanks for All the Fish" (Douglas Adams) | \--------------------------------------------------------/