Support Notes for Red Hat Enterprise Linux AS v.4.6 for HP Integrity Servers

12. This issue affects Linux running on all Integrity systems.
The Management Processor UART on these systems does not supply the Carrier Detect
signal. This causes applications to hang when opening the UART device, waiting for Carrier
Detect, unless they use the O_NDELAY or O_NONBLOCK flag.
For example, echo foo > /dev/ttyS0 hangs.
This is usually not a problem because /dev/ttyS0 is usually used as a console, the agetty
process opens it with O_NONBLOCK, and processes spawned by agetty generally inherit
the already-opened device.
However, there are some cases where the device must be opened again, and applications
will observe the hang.
You may also need to add the -L option to the agetty line in the /etc/inittab file as show
below to resolve the problem:
co:2345:respawn:/sbin/agetty -L ttyS0 9600 vt100-nav
After editing the file, signal the init process to re-read the inittab file with the following
command:
kill -HUP 1
If you are logged in to the console, then exit and log in again to restart the agetty.
13. Before booting Red Hat Enterprise Linux AS v.3 or v.4 on an nPartition on an rx7620, rx8620,
or Integrity Superdome server, your ACPI configuration value must be set to
single-pci-domain acpi flag to eliminate any bus address conflicts and ensure all I/O
slots have a unique address. Although your server should have the correct setting already,
confirm it before proceeding and change it if necessary using the following instructions:
a. From the EFI shell, enter acpiconfig.
b. You should see the following output:
acpiconfig settings: single-pci-domain
If you see something different, continue to the next step to reset the value. Otherwise,
stop here.
c. To set the ACPI configuration value to single-pci-domain:
1. From the EFI shell, enter acpiconfig single-pci-domain.
2. You should see the following output:
single-pci-domain settings have been enabled. A reset is
required for the settings to take effect.
d. Enter reset.
14. If you want rx7620, rx7640, rx8620, or rx8640 server hardware to power off when the
shutdown -h comand or poweroff command is issued, run the acpiconfig enable
softpowerdown command from the EFI shell and reset the nPartition to make the ACPI
configuration take effect.
The normal behavior on these servers is for an nPartition to be made inactive (all cells are
in a boot-is-blocked state) when shutdown -h or poweroff is issued from the Red Hat
Linux command line. This behavior is established with the acpiconfig disable
powerdown setting, which is the normal setting for the single-pci-domain ACPI configuration.
On HP Integrity Superdome servers, an nPartition is always made inactive when halted
from the operating system (for example, after shutdown -h), and this behavior cannot be
changed.
When softpowerdown is enabled on an rx7620, rx7640, rx8620, or rx8640 server, if one
nPartition is defined in the server then halting the operating system powers off the server
cabinet (including all cells and I/O chassis). On an rx7620 or rx8620 server with multiple
Known Issues 9