Subject: Re: amd64 syscall.c question
To: Andrew Doran <firstname.lastname@example.org>
From: David Laight <email@example.com>
Date: 06/06/2007 21:12:23
On Wed, Jun 06, 2007 at 09:01:44PM +0100, Andrew Doran wrote:
> On Wed, Jun 06, 2007 at 03:39:29PM -0400, Blair Sadewitz wrote:
> > BTW, what is the operational distinction between syscall_plain() and
> > syscall_fancy()?
> Fancy handles tracing (like ktrace), plain does not. The syscall handler is
> noted in struct mdproc and entered through an indirect call. For CPUs that
> actually matter, indirect calls are more expensive than a couple of simple
> test+branch pairs, and maintaining 2x the number of syscall paths is a pain.
> So they should be merged.
Isn't that indirection also used for the emulation system call entry?
But I do agree that having 2 copies of the same code is stupid.
David Laight: firstname.lastname@example.org