cvs commit: src/sys/alpha/alpha support.s src/sys/i386/i386 identcpu.c support.s src/sys/i386/include md_var.h src/sys/i386/isa npx.c src/sys/ia64/ia64 support.s src/sys/powerpc/powerpc bcopy.c src/sys/sparc64/sparc64 support.S ...

[Dag-ErlingSmørgrav]

Kris Kennaway <kris at obsecurity.org> writes:
> On Fri, Apr 04, 2003 at 09:29:55AM -0800, Dag-Erling Smorgrav wrote:
> >   Define ovbcopy() as a macro which expands to the equivalent bcopy() call,
> >   to take care of the KAME IPv6 code which needs ovbcopy() because NetBSD's
> >   bcopy() doesn't handle overlap like ours.
> Was this for optimization reasons, hysterical raisins, or some other reason?

The existence of ovbcopy()?  I imagine it was just an API issue,
someone didn't feel comfortable assuming that the kernel bcopy()
handles overlap when the userland version doesn't.  In FreeBSD
however, ovbcopy() has always (for appropriate values of "always")
been an alias for or duplicate of bcopy().  On i386, ovbcopy() was an
alternate name for bcopy from its inception in revision 1.1 of
locore.s (originally from 386BSD) until revision 1.40 (late 1996) when
Bruce made it a trampoline (and bcopy() a function pointer) to allow
for multiple processor-specific versions.  On powerpc, it was a
separate function but an exact duplicate of bcopy() (which itself is a
wrapper for memcpy()).  On all other platforms, it was an alternate
name for bcopy().

In NetBSD, the situation is a little confused, because most platforms
use a generic C implementation of bcopy() (in libkern) which handles
overlap, but some use optimized assembler versions which don't, and
these platforms have ovbcopy() - but the only part of the tree which
actually uses ovbcopy() is the IPv6 stack (KAME), and it has its own
version (a macro wrapper for memmove()) so in effect the real
ovbcopy() is never used.

The current situation in FreeBSD (after my commits) is much like that
in NetBSD, except we have no real ovbcopy() at all, just a macro in
<sys/systm.h> for KAME's benefit.

DES
-- 
Dag-Erling Smørgrav - des at ofug.org