Message-ID: <3C47055C.3010103@zytor.com>
Date: Thu, 17 Jan 2002 09:09:48 -0800
From: "H. Peter Anvin" <hpa@zytor.com>
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To: vda@port.imtp.ilyichevsk.odessa.ua
CC: linux-kernel@vger.kernel.org
Subject: Re: [ANNC] Linld 0.94 available
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Denis Vlasenko wrote:

> 
> Ok, I brought old Turbo Debugger from home...
> 
> It is not true on this box I type this message right now. 128 MB RAM.
> Under DOS:
> INT 15 AX=E801 returns carry set and AH=86 (have no BIOS manual here to look 
> up this error code), other registers unchanged.


AH=86 is function not supported.

However, once again, you're running UNDER DOS.  You probably should 
query HIMEM.SYS for the memory size,


> INT 15 AH=88 returns AX=0.
> INT 15 AX=E820 - not tested, but obviously not working (or else kernels would 
> boot fine without linld/loadlin kludge or kernel patch)
> 
> So we have "triple-0" failure extracting mem size info from INT 15.


... because you're running under DOS.

> 
> Just imagine old lovely 486 box never tested by manufacturer to work well 
> with 64 MB of RAM. Joe Random Hacker plays Meg-o-Rama, but BIOS does not 
> understand how that can be: int 15 fn 88 does not fit in 16-bit reg?!
> DOS does not boot, Joe says: well, Linux rulez, it will boot! but no...
> 
> OTOH, CMOS reading hack most probably would not work either... memscan time?
> 


By the time 64 MB RAM became supported, INT 15 AX=E801 was already 
common.  For pathological cases like you describe, it's "mem=" time.

	-hpa


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