Wouter Coene wrote:
>
> Hi,
>
> I just realized that in order to be able to write to memory addresses above
> 0x100000 linear (1 Mb), even in protected mode, the A20 line has to be
> enabled. However, greppig through the current NILO source tree for 'A20',
> '8042' (the chip that controls this line) and '0x64' (the I/O port of said
> chip) gave no relevant results, so I assume that the A20 was never enabled
> by the current NILO source. If that is true, then that could be the problem.
>
> Some background:
>
> The A20 line was introduced by, I believe, Intel engineers, to be able to
> run programs written for the 8086/8088 which relied on the address
> wraparound feature of these processors, on the 80286 and higher.
Actually, IBM engineers.
Anyway, for a *thouroughly* run-through-the-grinder A20 cdoe, I would
suggest look at SYSLINUX. The code currently in the Linux kernel is
actually based on a somewhat older version of the SYSLINUX code.
-hpa
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