Re: [uml-devel] high-performance system calls using vsyscall

[Jeff D. <jd...@ad...>]

On Tue, Jan 17, 2006 at 01:04:21AM +0100, Blaisorblade wrote:
> No, wrong - on x86 it's used for everything, depending on userspace (it's 
> replacing int 0x80 with sysenter). For some reason, on x86-64 it was that 
> way, but it switched to what you say (implementing only a few syscalls 
> directly in userspace).

Yeah, I was remembering Andrea's original proposal to implement a few system
calls entirely in userspace.

> > In a tt-style UML, where the UML kernel is in the same address space
> > as the process, this could be used for all system calls, where you
> > would just jump from there into the UML kernel.
> 
> 1st, TT mode is kept there only until SKAS0 will be damn stable (it seems 
> we're probably reaching that, no foreseen problems, except maybe my new TLS 
> code doesn't work for SKAS0 yet IMHO), and because it's the only SMP 
> supporting mode.

It has worked fine for me since I fixed that one bug.

				Jeff