> 1) It's faster and simpler.  The eflags register is saved by the CPU
> automatically on entering a trap gate, and we can just turn off the
> trace bit in trap() if we get a single-step interrupt from kernel mode
> on the first instruction of the syscall handler.
> 

  It's definitely better.

> 
> 3) Programs using VM86 mode (i.e. pcemu or dosemu) can do system calls
> directly from 16-bit code, rather than having to switch to a 32-bit
> code segment first.  Thus they will be faster.  (They'll still have to
> fiddle with the stack a bit so that the kernel will know where to find
> the syscall arguments.)

 Is it currently possible to use V86 mode ?
 AFAIK pcemu emulates each instruction in software.

Zdenek Salvet
salvet@nyx.dcs.muni.cz