On Fri, 29 Jul 2011 18:44:06 -0400 Greg Troxel <[email protected]> wrote:
> > Anyone knows what is the etimology for softc? > What does it mean? Where does it come from? When was it first used? > > In PDP-11 context, CSR means "control and status register". Often there > was an address (for a 16-bit word) that was for control and status, and > another one for data. For example, the DL-11 (and DLV-11 on QBUS) had a > receive CSR at 177560, and receive data at 177562*. I have always > interpreted softc as "software c(control/status)", being data that the > driver keeps state on, but which is not stored in the hardware. > > I remember softc being present in 2.8BSD, probably mid 80s, and I would > guess that it was introduced very early in the BSD days, in the original > networking code. serial devices don't need so much state, and the > information that is in the softc in a network device (queues, etc.) are > in the tty structure, roughly analogous to the common ethernet data > structure. > > > * http://www.fpns.net/willy/pdp11/pdptrbsh.htm (seems accurate from my memory) This seems to confirm some of your theory: http://www.tamacom.com/tour/kernel/bsd/S/676.html This code mentions it as 'soft carrier' in a comment, but I have found no other references to it: http://www.tamacom.com/tour/kernel/bsd/S/758.html#L140 -- NetBSD - Simplicity is prerequisite for reliability
