Re: Interesting Emulation/Project idea for Linux.

H. Peter Anvin (
Wed, 9 Apr 1997 20:54:40 -0700 (PDT)

> On Wed, 9 Apr 1997, Alan Cox wrote:
> > > various platforms available, what is stopping someone from
> > > adding hooks to the kernel to provide low-level system services
> > > to these emulators? Seems
> > Because they on the whole don't need any. The ones that do are DOSemu ELKS
> > and wine. Those use vm86 and modify_ldt which are in the kernel. Generally
> > speaking emulators don't need kernel help. Only those that use processor
> > resources and modes.
> Sure, but wouldn't it be a heck of a lot faster (potentially) to do it
> that way? Seems like people are always expounding upon the glories of
> kernel-mode code.... =)

In general, sticking stuff in the kernel is a bad idea. Putting
something in the kernel is usually only warranted if it would result
in a *massive* performance improvement, eliminate security flaws or
simply cannot be done in user space.

In this particular case I don't think either applies: simulating a
foreign architecture is best done completely in user space.