System will hang when booting with a terminal attached to the serial port.

To verify that you are having this issue, perform a verbose boot.

ok boot -v      

The following example is the output from an Ultra[TM] 5:

ok boot -v
Boot device: /pci@1f,0/pci@1,1/ide@3/disk@0,0 File and args: -v
Loading ufs-file-system package 1.4 04 Aug 1995 13:02:54.
FCode UFS Reader 1.11 97/07/10 16:19:15.
Loading: /platform/SUNW,Ultra-5_10/ufsboot
Loading: /platform/sun4u/ufsboot
SunOS Release 5.8 Version Generic_108528-13 64-bit
Copyright 1983-2001 Sun Microsystems, Inc. All rights reserved.
Etherrnet address = 8:0:20:a8:fa:8a
mem= 524288K (0x20000000)
avail mem = 510238720
root nexus = Sun Ultra 5/10 UPA/PCI (UltraSPARC-IIi 333MHz)
pcipsy0 at root: UPA 0x1f 0x0
pcipsy0 is /pci@1f,0
PCI-device: pci@1,1, simba0
simba0 is /pci@1f,0/pci@1,1
PCI-device: pci@1, simba1
simba1 is /pci@1f,0/pci@1
PCI-device: ide@3, uata0
uata0 is /pci@1f,0/pci@1,1/ide@3
dad0 at pci1095,6460 target 0 lun 0
dad0 is /pci@1f,0/pci@1,1/ide@3/dad@0,0
<ST320414A cyl 39533 alt 2 hd 16 sec 63>
dad1 at pci1095,6460 target 1 lun 0
dad1 is /pci@1f,0/pci@1,1/ide@3/dad@1,0
<ST320414A cyl 39533 alt 2 hd 16 sec 63>
root on /pci@1f,0/pci@1,1/ide@3/disk@0,0:a fstype ufs
PCI-device: ebus@1, ebus0
power0 at ebus0: offset 14,724000
power0 is /pci@1f,0/pci@1,1/ebus@1/power@14,724000
su0 at ebus0: offset 14,3083f8
su0 is /pci@1f,0/pci@1,1/ebus@1/su@14,3083f8
su1 at ebus0: offset 14,3062f8
su1 is /pci@1f,0/pci@1,1/ebus@1/su@14,3062f8
se0 at ebus0: offset 14,400000
se0 is /pci@1f,0/pci@1,1/ebus@1/se@14,400000 <---- notice that the system stops here
EBus sub-system Device Bus
Siemens Serial port controller      

Other systems may look a little different. What is important to note is that the system hangs when it accesses the serial port.

How does this happen?

One way this can happen is if the customer uses admintool to change settings on the serial port. When the changes are applied it often changes the ttya-ignore-cd variable to false. This causes a problem during the boot because the system will stop at the serial port and expect a response from the terminal.

To remedy the problem perform the following steps:

1. At the ok prompt type:

ok printenv ttya-ignore-cd      

2. If this parameter is set to false, then set this parameter to true:

ok setenv ttya-ignore-cd true      

3. Reset the system:

ok reset-all      

The system should now boot and not hang at the serial port.

Keywords: boot, serial, hang