Patch-ID# 100225-02
Keywords: ALM2, serial port, hangs, printer hangs, serial patch
Synopsis: SunOS 4.1, 4.1.1, 4.1_PSR_A :printers, terminals, plotters, hang on serial and ALM2 ports.
Date: Feb 15,1991
 
SunOS release: 4.1, 4.1.1, 4.1_PSR_A
 
Topic: ALM2 and serial port patch fixes flow control hang problems.
 
BugId's fixed with this patch: 1048128

Architectures for which this patch is available: 
Sun3, Sun3x, Sun4, Sun4c

Patches which may conflict with this patch: 100137-01 100200-01 100187-01 100188-01

Obsoleted by: SysV_Rel4

Problem Description:

BugID 1048128:
When sending output to printers, terminals, plotters etc. using
the ALM2 or zs serial ports with the xon/xoff flow control, the
output may hang intermittently.

Flow control problems exist in SunOS 4.1, and 4.1.1.  After some
extended period of time, the device would send an xoff, and data
would stop.  When data is to be resumed with an xon from the device,
the xon seems to have been dropped or ignored because data flow did
not continue.

INSTALL:

As root:

save the previous system files:
mv /sys/sun{3,3x,4,4c}/OBJ/mcp_async.o mcp_async.o.orig  [only if using an ALM2]
mv /sys/sun{3,3x,4,4c}/OBJ/tty_ldterm.o tty_ldterm.o.orig

install the new files into the system configuration area:
cp sun{3,3x,4,4c,4-490}/{4.1, 4.1_PSR_A,4.1.1}/mcp_async.o /sys/sun{3,3x,4,4c}/OBJ [only if using an ALM2]
cp sun{3,3x,4,4c,4-490}/{4.1,4.1_PSR_A,4.1.1}/tty_ldterm.o /sys/sun{3,3x,4,4c}/OBJ


rebuild the kernel, save /vmunix to /vmunix.save
copy the new vmunix to /vmunix 
and reboot the machine.


to verify proper installation of the new patch
after rebooting on the new kernel type: 

what /vmunix | grep tty_ldterm   
what /vmunix | grep mcp_async   [only if using the ALM2]

you should see
tty_ldterm.c 1.47 91/02/15 serial patch
mcp_async.c 1.41 91/02/15 Copyr 1989 Sun Micro serial patch