On 1/14/2014 8:38 PM, Charles Steinkuehler wrote:
> On 1/14/2014 5:34 AM, andy pugh wrote:
>> Someone on the forum is trying to write a driver for some onboard GPIO
>> that needs to be enabled via an INT 15. The sample assembler is:
>>
>> MOV AX, 6F08H        Sets the digital port as input
>> INT 15H                     Initiates the INT 15H
>>
>> Is it reasonable/legitimate to do this with inline assembler in a .comp file?
>>
>> Having never tried to use inline assembler, what would it look like? I
>> guess we need to put ax back to where it was afterwards?
>>
>> Is there  a linux system call to achieve the same result?
> 
> Not to derail this thread from the "I used to have to enter hex machine
> instructions by hand with toggle switches, and it was up-hill both
> ways!" reminiscing, but it should be OK to do an INT instruction or make
> kernel calls in the setup portion of a HAL component.  Of course the
> execution mode and the interrupt need to agree on things like the
> current operating context of the CPU (no calling 16-bit BIOS routines
> from 32-bit PAE code!).

I was reading a bit more about this today, and apparently how the
graphics applications do this is to include a virtual x86 machines for
the sole purpose of being able to execute INT calls to the on-board
video BIOS for GPUs (which is the only way they can be properly setup on
some systems, particularly non-x86 machines with undocumented hardware
and closed-source GPU drivers).

-- 
Charles Steinkuehler
[email protected]

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