COMPAT_43TTY and MPSAFE tty

[Ed Schouten]

Hello Olivier,

* Olivier SMEDTS <olivier at gid0.org> wrote:
> Is it safe to run a kernel without options COMPAT_43TTY since the new
> MPSAFE tty layer was introduced ?
> I removed it from my kernel config file since few days and didn't
> notice any change...
> I use nearly latest -CURRENT on amd64 and never tried removing this
> option before because of the big "KEEP THIS!". Now I don't use any
> COMPAT_* option.

If you compiled your applications after June 14, everything should just
work (not taking binary-only applications into account). Even if you did
not, there is a slim chance your application depends on COMPAT_43TTY.

COMPAT_43TTY only introduces some binary-only compatibility interfaces
(ioctls) for applications that used <sgtty.h>. I already removed
<sgtty.h> before I imported MPSAFE TTY:

	http://www.freebsd.org/cgi/cvsweb.cgi/src/include/Attic/sgtty.h

I guess we'd better keep COMPAT_43TTY in our stock kernel configuration
files for another couple of years, but maybe we should already remove
the "[KEEP THIS!]" message.

It's also possible to remove "device pty" from your kernel configuration
file. If you remove this line, you can only allocate pts(4)-style
pseudo-terminals (/dev/pts/...). This means you cannot allocate any
pseudo-terminals inside a FreeBSD 4/5/6/7 jail. I guess we should keep
"device pty" a little longer than COMPAT_43TTY, because recompiling
applications won't migrate the offending ones to pts(4).

-- 
 Ed Schouten <ed at 80386.nl>
 WWW: http://80386.nl/
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