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SubjectRe: What is System.map for?
DateThu, 16 Jan 1997 08:40:08 +0000
FromDavid A Rusling <>
> On Wed, 15 Jan 1997, Sheldon E. Newhouse wrote:
> 
> > Can anyone give me some ideas and/or reference about System.map? I am
> > using /arch/i386.  
> > 
> > 1. What is System.map required for? 
> > 2. How does the kernel use it?
> > 3. I removed it from one of my systems, and, at least for basic stuff,
> > it seems to make no difference. 
> 
> The System.map is your kernel's symbol table, and it's needed to load
> modules that use symbols that are internal to the kernel (e.g. most
> modules, if not all). If you aren't using modules, I don't think it's used
> unless you are doing debugging, or stack traces and such. Might want to
> keep it around tho.
> 

Nope, that's not true.  Apart from 'ps', the modules package interacts with
the kernel via system calls that, as well as loading/unloading the modules
exchange and merge exported system symbols.  Modules are relocatable partially
linked images that are fixed up at run time (when the symbols and the load 
addresses are known).  Exported system symbols can  be seen via /proc/ksyms and
the ksyms utility will display this logically (ie module by module).  

Oh, and as modules always live in /lib/modules then I do not see any reason to
rename them.

Dave

----------------------------------------------------------------------
David A Rusling				Principal Engineer
European Semiconductor Applications	Digital Equipment Co Ltd.,
	Engineering			PO Box 121,
					Imperial Way,
					Worton Grange
					Reading RG2 0TU
Linux, Alpha, StrongArm, PCI		Tel: UK-(0)1734-204380
					Fax: UK-(0)1734-203133
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