Followup to: <Pine.LNX.3.95.1000525220139.6760A-100000@chaos.analogic.com>
By author: "Richard B. Johnson" <root@chaos.analogic.com>
In newsgroup: linux.dev.kernel
>
> Does anybody really know what BIOS function 0xe801, interrupt
> 0x15 is supposed to return? I mean, by specification, not conjecture.
> None of my BIOS books show a spec for this function number.
>
> Relevant Linux boot code follows. It implies that register ax is
> supposed to contain so-called "base-memory", i.e., 640k (in kilobytes)
> and register bx is supposed to contain so-called "extended-memory", i.e.,
> memory above 1 megabyte (in 64 kilobyte chunks).
>
The interrupt list is your friend.
>
> This works on most systems, I am sure. However, I have two motherboards
> which contain a BIOS that confuses Linux, requiring a "MEM=" entry
> to boot. Otherwise I get a seg-fault in the kernel while memory is being
> organized.
>
> This is from the so-called "stable" kernels, ../boot/setup.S. This has
> been changed on later kernels to use GAS, but the logic is the same.
>
Can you do this under plain DOS (no CONFIG.SYS, no AUTOEXEC.BAT):
debug
a
mov ax,e801
int 15
int 3
g=100
q
... and let us know what the output is?
As for how the interrupt works, Ralf Brown's Interrupt List is the bible...
-hpa
-- <hpa@transmeta.com> at work, <hpa@zytor.com> in private! "Unix gives you enough rope to shoot yourself in the foot."- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.rutgers.edu Please read the FAQ at http://www.tux.org/lkml/
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