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Re: x86 BIOS functions?


rdim_outside@softhome.net writes:

> Does anybody know an easest way to use standard PC BIOS functions under
> eCos? I mean, I wouldn't like to rewrite - for example - floppy
> functionality or VGA graphics mode switching... 
> 
> Related question to eCos experts: I seen how IDE operations are implemented
> on PC platform - why don't use fios calls to implement this HAL?
> 

eCos runs in 32 bit protected mode. The BIOS operates in 16 bit real
mode. While it is theoretically possible to switch modes to make BIOS
calls, it is complex, error prone, has issues with addressing and
would severely impact interrupt latency. So we do not do it. Most PC
hardware is fairly straightforward, so it is easier to program it
directly from protected mode.

-- 
Nick Garnett, eCos Kernel Architect
Red Hat, Cambridge, UK


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