Messages in this thread |  | | | From | (H. Peter Anvin) | | Subject | Re: Problems with to large of a kernel | | Date | 2 Dec 1998 06:33:21 GMT |
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Followup to: <Pine.LNX.3.95.981201144105.6994A-100000@chaos.analogic.com> By author: "Richard B. Johnson" <root@chaos.analogic.com> In newsgroup: linux.dev.kernel > BzImage kernels use the BIOS INT 0x15 'memory copy' function to put > the kernel at its final resting place of offset 1 megabyte which > is unreachable in the 16-bit segment:offset world. Since this function > is enabled and tested by the BIOS as part of the memory check, it is > not too likely that it is broken. There was a problem with stuck > A-20 bits in early '386 machines that used the keyboard controller > to enable it. Basically, you had to wait a few microseconds to have > it take affect, since the keyboard controller is really its own CPU > with embeded software that takes time to do its thing. A BIOS would > certainly "know" the time to wait, so it would be embeded in the > INT 0x15 code. The problem occurs when a user program tries to enable > the bit and expects an instant response. >
Ah, yes; if the INT 15h memory copy function wasn't so bloody broken it might actually be usable. *Sigh* It was of course too much IQ required for anyone to have defined an A20 on/off BIOS function.
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