[TUHS] V6 networking & alarm syscall

[reed at reedmedia.net]

On Fri, 11 Jan 2019, Clem Cole wrote:

> Right and select(2) was created by Sam and wnj during the 4.2 development.?
> I've forgotten which sub-version (it was in 4.1c, but it might have been in
> b or a before that).? There was a lot of arguing at the time about it's need;?
> the multiple process solution was considered more 'Unix-like.'
...

I search through the SCCS code in 4.1c. There is a reference to it by 
name for 4.1a in syscalls.c (82/11/13) to answer your comment.

"#38 -- 4.1a select",   /*  38 = nosys */

The select system call was added in 81/02/07 with no comment. Commit 
history shows in 81/10/17: "cleanup (mpx removal, old tty removal, 
beginnings of select)" and in 81/10/11 "first boot with select()" which 
includes lots of changes like replace lots of tty code and use 
selwakeup().

But I don't see any of the select code itself until a new file 
kern_descrip.c was introduced in 82/07/15. Soon after the #38 select 
became obsoleted oselect and a new syscall number #93 was assigned.
(In 4.2 the select code was in sys_generic.c.)

Can someone tell me about SCCS behaviour when renaming/moving or 
deleting files? In particular, I think the select() code prior to 
82/07/15 had different source filenames that no longer exist and the 
SCCS history was lost.  Anyone else have ideas about this?  I have 
noticed this with other SCCS spelunking where code was removed and then 
corresponding "s" files were missing -- but maybe that is just the way 
the systems that our current snapshots (McKusick discs) of this history 
were made from. Maybe sccs didn't checkout the history of deleted files 
by default (that is my guess).