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 A undocumented question? RAM shadow in Linux

I have a question about the RAM shadow under linux. Here is an paragraph
that I quoted from an reference guide of an vesa motherboard which use
the AMI BIOS:

        UNIX  and XENIX operarting systems by passes conventional single
user BIOS and contain their own hardware interrupt service routines. It
os necessary ro enable the main BIOS shadow(system BIOS and video BIOS)
option for proper installation from flooppy drive. Please remember to
disable the shadow RAM option after the operating system is installed
on the hard disk!

Is this apply to the Linux also? I have an phonix bios (11/15/88) in
my Gateway 486DX2-50 system. Every time I start the slackware 1.1.1
it always say bios test failed, however I never had problem with
the bios except see this message every time I reboot the machine. Is
it anthing do with bios shadow?

Any idea? suggestion? Please feel free reply by following up post,
but please drop me an email also!! thanks!

James Zhu
j...@phys.physics.ucf.edu

--
**********************************$$*******************************************
*       James Zhu               $$$$$$             Finger me for sure         *
* j...@phys.physics.ucf.edu    $$$ || $$$      If I am the right guy for you!! *
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 Fri, 05 Jul 1996 04:15:48 GMT   
 A undocumented question? RAM shadow in Linux
j...@physics.ucf.edu (James M. Zhu) writes:

'I have a question about the RAM shadow under linux. Here is an paragraph
'that I quoted from an reference guide of an vesa motherboard which use
'the AMI BIOS:

'       UNIX  and XENIX operarting systems by passes conventional single
'user BIOS and contain their own hardware interrupt service routines. It
'is necessary to enable the main BIOS shadow(system BIOS and video BIOS)
'option for proper installation from flooppy drive. Please remember to
'disable the shadow RAM option after the operating system is installed
'on the hard disk!

The paragraph does sound wrong, you could turn off RAM shadowing
before installing UNIX and XENIX ? RAM shadowing only affected speed
as far as I have heard ( as it does on my MG 386 ISA motherboard ..).

(ROM shadowing speeds up BIOS operation on  an uncached motherboard,
as the ROM's are slow ; caching is used to speed up such things as
well, if possible .. some motherboard/bios/other cards like scsi etc
combinations may have trouble caching bios. )

The truth is that Linux will not use any memory in the 640k-1meg
address range. That means if having no BIOS shadowing will mean
256/384 k more RAM, then you can try to run linux without shadowing.

There maybe (As on my motherboard/AMI bios) another option to do this
remapping (or probably more accurately, not do the remapping) of this
640k-1meg memory, to give more extended memory (addresses 1meg and
more).Or it may be automatic if no shadowing is enabled.

So, you can try turning off all shadowing, and having the memory that
frees up made available to linux by having it mapped to the extended
memory addresses ( physical addresses 10000h and above ).

if it doesnt work, then perhaps your motherboard needs shadowing to
have the roms visible ( which would make the statement about the
UNIX/XENIX  installation correct ?..) I think the statements about
UNIX/XENIX are plain wrong. the ROM shadowing would not affect
either the installation or operation of the UNIX/XENIX, except that
ROM shadowing uses part of the extended memory (384k?) so turn it off
to have the most memory usable.

'Is this apply to the Linux also? I have an phonix bios (11/15/88) in
'my Gateway 486DX2-50 system. Every time I start the slackware 1.1.1
'it always say bios test failed, however I never had problem with
'the bios except see this message every time I reboot the machine. Is
'it anthing do with bios shadow?
no, the kernel is just scanning for scsi cards or something, and the
bios isnt recognised (it doesnt exist) so it spits up a vague message.

'Any idea? suggestion? Please feel free reply by following up post,
'but please drop me an email also!! thanks!

'James Zhu
'...@phys.physics.ucf.edu

'--
'**********************************$$*******************************************
'*       James Zhu               $$$$$$             Finger me for sure         *
'* j...@phys.physics.ucf.edu    $$$ || $$$      If I am the right guy for you!! *
'*******************************************************************************



 Mon, 08 Jul 1996 09:07:13 GMT   
 
   [ 2 post ] 

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