FreeBSD system call implementation

[Peter Pentchev]

On Wed, Dec 15, 2004 at 07:56:53AM -0800, Kamal R. Prasad wrote:
> 
> --- Andrey Simonenko <simon at comsys.ntu-kpi.kiev.ua>
> wrote:
> 
> > On Wed, Dec 15, 2004 at 08:19:05PM +0530, Ravi
> > Krishna wrote:
> > 
> > > My question is why we store the
> > p->p_sysent->sv_table
> > > for each process. What is the reason for keeping
> > this per process?
> > > Are there some situations where two processes can
> > have different system calls
> > > available?
> > 
> > Processes can have different p_sysent, because the
> > kernel supports
> > different ABIs.  sv_entry (pointer to some system
> > call table) is
> 
> Sounds rather inefficient to have a per-process table
> rather than a set of ABIs into which the per process
> table is an indirection (similar to say vnops).

Errrr... actually, if you look at <sys/proc.h>, you'll see that this is
exactly the way it is - p->p_sysent is a *pointer* to a struct sysentvec,
and there are only a few struct sysentvec's in the kernel, definitely not
one per process :)

G'luck,
Peter

-- 
Peter Pentchev	roam at ringlet.net    roam at cnsys.bg    roam at FreeBSD.org
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