virtual device drivers?

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2 total messages Started by pstlb Wed, 07 Oct 1992 03:27

#580

Author: pstlb
Date: Wed, 07 Oct 1992 03:27

26 lines
1939 bytes


  I had read a post, a reply to someone asking about trapping I/O port accesses
under 386 p.mode, and the reply said that it could be done using a virtual
device driver.....  

  My question, then, is this:  how does one write a virtual device driver?  how
is it different from a 'regular' device driver?  and, can it be done with Turbo
Assembler?  

  also, I'd like to know how to switch into protected mode (i.e. an interrupt
call, changing the value of a "special" cpu register, etc.).....  386 protected
mode, not 286.....  all the different ways, if at all possible.....  


  please email me.....  I know it's supposedly bad etiquette, but I have a lot
of homework, which precludes me from checking this newsgroup frequently..... :)

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Re: virtual device drivers?

#584

Author: Jerzy Tarasiuk
Date: Thu, 08 Oct 1992 17:14

15 lines
1560 bytes

>>>>> On 7 Oct 92 03:27:49 GMT, pstlb@acad2.alaska.edu said:
p>   I had read a post, a reply to someone asking about trapping I/O port accesses
p> under 386 p.mode, and the reply said that it could be done using a virtual
p> device driver.....  
p>   My question, then, is this:  how does one write a virtual device driver?  how
p> is it different from a 'regular' device driver?  and, can it be done with Turbo
Seems someone meant 'driver for managing virtual 8086 mode'.
Of course Turbo Assembler can be used to write such a driver.
p>   also, I'd like to know how to switch into protected mode (i.e. an interrupt
p> call, changing the value of a "special" cpu register, etc.).....  386 protected
BIOS has routine to switch to 286 protected mode, simplest way
to switch to 386 protected mode is far jump or call to 32-bit code
segment (may be little problem, cannot load EIP on this jump because
in 286 PM CPU reads only 16 bit offset) or to 386 Task State Segment
(this should be recomended way, need load Task Register before jump).

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