Support Notes for Red Hat Enterprise Linux AS 4.7 for HP Integrity Servers

Console
• System appears to hang during installation or boot
If the system appears to hang during boot or installation, messages similar to the following
are displayed:
Loading initrd initrd-2.6.9-68.EL.img...done
This can occur when the firmware setting for the primary console is not set correctly for the
console device being used.
Use the EFI Boot Manager interface, that is initiated during the power on sequence, to set
the system console firmware properly for the device being used by choosing one of the
following:
— If the device is a keyboard, VGA, or mouse (KVM), then set (or confirm) the firmware
setting for the primary console to VGA as follows:
1. Select the Boot Configuration option then press ENTER to display the Boot
Configuration menu.
2. Select Console Configuration then press ENTER to select it.
3. Select the VGA entry then press P.
4. Press ESC to return to the previous menu.
5. Press Y to save the new console setting.
— If the device is a serial device such as a terminal emulator, then set (or confirm) the
firmware setting for the primary console to Serial as follows:
1. Select the Boot Configuration option then press ENTER to display the Boot
Configuration menu.
2. Select Console Configuration then press ENTER to select it.
3. Select the Serial entry then press P.
4. Press ESC to return to the previous menu.
5. Press Y to save the new console setting.
6. Exit from the EFI Boot Manager to the Linux boot prompt then enter:
ELILO Boot: console=ttyS0
• Use of a serial console when a VGA card is present
If the Red Hat kernel detects a VGA card, it defaults to using the VGA display as system
console.
To use serial console, use the EFI Boot Manager to select the serial device as the primary (or
only) console device as described in the previous issue.
• Applications may hang when opening Management Processor UART
The Management Processor (MP) UART on all HP Integrity servers running RHEL do not
supply the carrier detect signal. This causes applications to hang when opening the UART
device because no carrier detect is sent unless the O_NDELAY or O_NONBLOCK flag is set.
For example, the command echo foo > /dev/ttyS0 would hang.
Typically, this is 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 so applications will observe the hang.
Use the following procedure to resolve the problem:
1. Add the -L option to the agetty line in the /etc/inittab file as follows:
co:2345:respawn:/sbin/agetty -L ttyS0 9600 vt100-nav
12 Recommendations, Limitations, and Known Issues