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 BIOS shadowing in Linux
Am I correct assuming that after boot-up Linux no longer uses the PC's own
system BIOS code?  If so, then shadowing
of the system BIOS through the PC BIOS is not just redundant for Linux but
even waste of memory, right?

On dual boot systems though, where we also can boot into DOS/Windows the PC
BIOS shadowing probably helps the
speed a great deal.  To accommodate the MS OS environments without screwing
it for Linux, the optimal solution
might be then to have system BIOS shadowing disabled in the PC BIOS and
enable it in the DOS/Windows CONFIG.SYS
file with the ROM switch of the EMM386.SYS command line.  Can somebody
confirm my speculation on this?

I also assume that shadowing video BIOS in the PC BIOS still could make
sense if the system memory is faster than
the video memory, right?


 Wed, 10 Jul 2002 03:00:00 GMT   
 BIOS shadowing in Linux


Well, superfluous rather than redundant.

Shadowed BIOS is not used by Win9x except when real-mode services
are required.  If your system doesn't need any real-mode services
(most modern systems shouldn't) the shadowed BIOS is just as much
a waste under Win9x as it is in linux.

For plain DOS or even Win3.x you may find some benefit in
retaining the BIOS shadowing.


-John (

 Wed, 10 Jul 2002 03:00:00 GMT   
 BIOS shadowing in Linux


Direct quote from Norton's dead-tree _Inside the PC_, Edition 8, page
"Windows 9x goes back to real mode much less often than Windows 3.x, but
it still goes back many times each second."

Whether Win9x actually uses the BIOS functions while in this state is
another question.  I suppose you could turn shadowing off, run a series
of benchcrafts, turn it back on, run the same benchcrafts, and see if
there's any difference....

To look at it another way, if both John Thompson and Peter Norton are
right, Win9x is not a Modern OS.  ;-)


 Wed, 10 Jul 2002 03:00:00 GMT   
 BIOS shadowing in Linux

I remember noticing a distinct difference with and without BIOS
shadowing when I used Win3.x many years ago.  But I honestly
don't use Win9x enough to have even tried this recently.

Hey, no argument from me...


-John (

 Thu, 11 Jul 2002 03:00:00 GMT   
   [ 4 post ] 

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