[svlug] Re: Linux on Opteron (kevin@ank.com)

J C Lawrence claw at kanga.nu
Fri Aug 29 13:41:32 PDT 2003

On Fri, 29 Aug 2003 12:39:52 -0700 
kevin  <kevin at ank.com> wrote:

> Turbo and SuSE both claim that x86-32 code will still run correctly
> under 64-bit Linux, but I suspect they mean that you can still load
> the 32 bit libraries against the 64-bit kernel.  What is needed are
> shunt libraries that will promote int's on the stack from 32-bit to
> 64-bit and then call the 64-bit routine.  Without that there will be
> memory contention between the 64 and 32 bit libraries, and several
> libraries I suspect won't be able to load simultaneously in 32 and 64
> bit versions -- kernel modules for example, or apache modules -- any
> kind of plug-in really.

The normal route for handling such strongly different ABIs is to do the
conversions inside the kernel, just inside the syscall interface.  That
way userspace doesn't have to change at all.  

One place this approach breaks down, and badly, is in handling IOCTLs,
which are of course UN cataloged.

J C Lawrence                
---------(*)                Satan, oscillate my metallic sonatas. 
claw at kanga.nu               He lived as a devil, eh?		  
http://www.kanga.nu/~claw/  Evil is a name of a foeman, as I live.

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