>> and i do not get the point in an int21 handler in >> emm386. because it already has an any-int handler! > > The way the V86 monitor now has to work is by intercepting all interrupts in > protected mode. > Then reissue the interrupt in V86 mode. when that interrupt comes back you get an iret to > protected mode, which then iret's back into the V86 code. > > These are 4 CPU mode switches.
That's not quite correct. The IRET in v86-mode does not magically switch back to protected mode (how should the CPU know which protected-mode address it has to jump to on a real-mode IRET?). So just 2 mode switches remain. If the VME extensions are enabled (a feature available in Pentium and better cpus) you can even get rid of those 2 remaining switches for software interrupts (IRQs and exceptions always will go through the IDT in v86-mode). But this gives only a small speed benefit, you can measure it with Jemm386. ------------------------------------------------------------------------- Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 _______________________________________________ Freedos-devel mailing list Freedos-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/freedos-devel
