Summary: Using >48 ptys in SunOS 4.1

Date: Fri Feb 01 1991 - 13:04:21 CST

Stated Problem:
        The release notes for 4.1 indicate that 256 ptys are supported,
but I cannot enable/use more than a maximum of 48 and the only reference
I find to increasing this limit in the manuals is to modify the kernell
config file which doesn't seem to work.

Problem Solution:

        It seems that I put too much effort into isolating and testing
the problem; incorrectly as it turns out. Increasing ptys does work as
advertised. However, several people indicated that they had also had
problems so here's the solution...


- First, edit kernel config file and change the pty specification to
include the number of ptys you need 48 - 256.

pseudo-device pty
pseudo-device pty 96

Note that several people indicated their config program does not accept
the space between pty and 96, they must use "pty96" instead. I was also
advised that win128 must be increased to be at least as large as pty.

- Second, build and install the new kernel and reboot.

- Finally, run /dev/MAKEDEV pty#, where # ::= 0-14 as needed. Each
invocation of pty creates 16 pty and tty files in /dev. It should
not be necessary to MAKEDEV pty[0-3].

MAKEDEV has the following mappings

pty0 {p,t}typ[0-f]
pty1 {p,t}tyq[0-f]
pty2 {p,t}tyr[0-f]
pty3 {p,t}tys[0-f]
pty4 {p,t}tyt[0-f]
pty10 {p,t}tyP[0-f]
pty14 {p,t}tyT[0-f]


So why didn't it work before? Well, I wanted to test the updated kernel
on my workstation first before rebooting the server. I was too lazy to
rlogin 48 times (I didn't have the available swap space either!) so I
commented tty{q,r,s} out of /etc/ttytab and deleted the associated /dev
entries. It seems that rlogind "knows" the correct order of pty
allocation so it doesn't check the /etc/ttytab file(grumble). Rlogind
gave up when /dev/ttyq0 didn't exist; and didn't bother to determine that
/dev/ttyt0 was available.

My thanks to all,
-Charles Ball

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