Date: Sun, 20 Jun 2004 10:50:00 -0600 (MDT) From: "M. Warner Losh" <imp@bsdimp.com> To: phk@phk.freebsd.dk Cc: arch@freebsd.org Subject: Re: [REVIEW] move tty lock/initial up in the stack Message-ID: <20040620.105000.106880101.imp@bsdimp.com> In-Reply-To: <82937.1087721102@critter.freebsd.dk> References: <20040619.145736.91276883.imp@bsdimp.com> <82937.1087721102@critter.freebsd.dk>
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In message: <82937.1087721102@critter.freebsd.dk>
"Poul-Henning Kamp" <phk@phk.freebsd.dk> writes:
: In an ideal world the hardware driver would be reduced to just that,
: a few simple primitives, "start", "config", "open", "close" and a
: backcall "rint" with received data and modem status changes. This
: is not too unlike what Marcel have done with uart(4)
I guess I'm curious how the tty/cua split would be done in this
scheme.
Of course I'm reimplementing the Cyclades Z driver to try to use
uart, which is why I'm getting curious. I don't know if this will
wind up working or not, but since 95% of the hardware interface is two
circular buffers in memory, which does seem to map mostly onto
Marcel's model. Time will tell... I also have porting the stallion
driver to current. I can do this by a simple hack on the old driver,
or a rewrite. I'll use my Z experience to decide.
: The major difference is that serial ports are rapidly headed into
: the sunset whereas disks are very much a hot topic.
I suspect that the decline will last for a long time. Many of the usb
devices that I've seen are really usb to rs232 to thing, so I suspect
that it is a case of 'Serial ports are dead, long live the serial
ports'
: The pty driver is the only really interesting tty driver these days
: as most terminal access is through sshd, telnetd or xterm.
There's still a lot of people using ppp for dialup connections, even
in the day of broadband. I suspect that will be the other large area
of heavy use.
: Currently I see two ways to get ptys out form under giant:
:
: 1) write an entirely new pty driver which is totally separate
: from the rest of the tty code (We don't need slip/ppp/netgraph
: support on ptys anyway).
:
: 2) clean up the tty code enough that the pty can be deGiantized,
: paving the road for the rest of the tty drivers to get the
: same treatment, should somebody else care enough.
Are you looking for help on the latter?
: I havn't quite made up my mind yet, and have resorted to some general
: polishing while I try to make sense of this stuff. To some extent I
: already regret getting my fingers dirty over here.
OK.
Warner
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