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From: rooij@bashful.isp.cft.philips.nl (Guido van Rooij)
Subject: Re: V86 mode & the BIOS (was Need advice: Which OS to port to?)
Message-ID: <1993Aug18.071548.5342@cnplss5.cnps.philips.nl>
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References: <107181@hydra.gatech.EDU> <1993Aug4.073826.24956@fcom.cc.utah.edu> <107725@hydra.gatech.EDU> <1993Aug9.224939.19834@fcom.cc.utah.edu> <108137@hydra.gatech.EDU> <BLYMN.93Aug12205126@mallee.awadi.com.au> <109151@hydra.gatech.EDU>
Date: Wed, 18 Aug 1993 07:15:48 GMT
Lines: 22
gt8134b@prism.gatech.EDU (Howlin' Bob) writes:
>In <BLYMN.93Aug12205126@mallee.awadi.com.au> blymn@awadi.com.au (Brett Lymn) writes:
>>Unfortunately, the v86 call is not a simple in *BSD, the method Linux
>>uses to change the task into v86 mode will not work due to differences
>>in the way the supervisor stack is used in *BSD (this is from memory,
>>I may have the wrong names but the concept is right I think).
>Hmm. All you have to do to enter V86 mode is to set the VM bit in
>the EFLAGS saved register. Are you saying that the kernel cannot
>modify the process's saved EFLAGS?
And then what happens when you want to do unpriviledged IO in vm86 mode?
I guess it isn't that simple.
-Guido
>--
>Robert Sanders
>Georgia Institute of Technology, Atlanta Georgia, 30332
>uucp: ...!{decvax,hplabs,ncar,purdue,rutgers}!gatech!prism!gt8134b
>Internet: gt8134b@prism.gatech.edu