Subject: Re: ancillary data alignment and binary backward compatibility
To: Chris G. Demetriou <,>
From: Matt Thomas <>
List: tech-net
Date: 03/08/2000 15:22:20
At 01:19 PM 3/8/00 , wrote:

>         hmm, it seems I was wrong about the choice... does the following
>         look like the right way?
>         - change syscall # of sendmsg and recvmsg.  
>         - add ALIGNBYTES to syscall argument for sendmsg/recvmsg.  it will be
>           added by syscall library (it means that, at least, libc and
>           user code must agree about ALIGNBYTES).
>           for old syscall #, ALIGNBYTES arg will be hardcoded into 3 at
>           kernel entry point.
>         - propagate alignment constraint value given from the userland into all
>           over the places like sys/netinet6, sys/netiso or sys/netccitt.
>         there's some incompatibility window for several weeks (with my
>         change that uses hw.alignbytes).

NO!  Leave things as they are.  The compat/netbsd32 code will need to re-layout 
any control data before passing to/from the user and native socket layer.  
KISS please.

Matt Thomas               Internet:
3am Software Foundry      WWW URL:
Cupertino, CA             Disclaimer: I avow all knowledge of this message