IBM Support

Linux cannot boot while GRUB has serial setting enabled - IBM iDataPlex dx340 Server (Type 7832)

Troubleshooting


Problem

GRUB hangs with a "GRUB Loading Stage2..." message when booting the Linux operating system with the three following settings enabled simultaneously: 1. The system has the Console Redirection function enabled on COM2. 2. SET Continue C.R. after POST to "on" in the BIOS setup menu. 3. COM2 Serial setting is enabled on the Linux operating system.

Resolving The Problem

Source

RETAIN tip: H193478

Symptom

GRUB hangs with a "GRUB Loading Stage2..." message when booting the Linux operating system with the three following settings enabled simultaneously:

  1. The system has the Console Redirection function enabled on COM2.
  2. SET [Continue C.R. after POST] to "on" in the BIOS setup menu.
  3. COM 2 Serial setting is enabled on the Linux operating system.

Affected configurations

The system may be any of the following IBM servers:

  • iDataPlex dx340 Server, type 7832, any model

This tip is not option specific.

This tip is not software specific.

Workaround

Complete one of the two methods below:

  1. After the operating system installation has completed, the user should change the field Continue C .R. after POST to disabled in the BIOS Setup.
  2. Modify the GRUB setting to disable serial functionality. This can be done by commenting out the serial configuration line within GRUB. See the following example.

Example:

  Edit /boot/grub/menu.lst
default=0
timeout=10
password --md5 $1$wwmIq64O$2vofKBDL9vZKeJyaKwIeT.

#serial --unit=1 --speed=57600 --word=8 --parity=no --stop=1
terminal --timeout=10 serial console
title Red Hat Linux (2.4.9-21)
root (hd0,0)
kernel /vmlinuz-2.4.9-21 ro root=/dev/hda6 console=tty0 console=ttyS1,57600n8
initrd /initrd-2.4.9-21.img
title Red Hat Linux (2.4.9-21) single user mode
lock
root (hd0,0)
kernel /vmlinuz-2.4.9-21 ro root=/dev/hda6 console=tty0 console=ttyS1,57600n8
initrd /initrd-2.4.9-21.img

To install the operating system via LAN1, complete the following instructions:

Remote Side

  1. Use the Serial over LAN utility to connect to the iDataPlex system
  2. When the iDataPlex system boots up, press F12 to boot from LAN. The System would start to install the Linux automatically.
  3. After finishing the operating system installation, the iDataPlex system should reboot into Linux from the hard drive.

iDataPlex System BIOS Setting

Example:

  Server --> Console Redirection
Com Port Address on-board COM1 port
Baud Rate 57.6K
Console Type VT-UTF8
FlowmControl None
Continue C.R. after POST Off

Boot --> Boot Device Priority
Boot priority order:
1. hard disk drive
2. LAN

PXE Server Setting

Example:

  default rhas4u6
timeout 100
prompt 1
display display.msg

label rhas4u6
kernel rhas4u6/vmlinuz
append initrd=rhas4u6/initrd.img linux text
console=ttyS1,57600n8r utf8 method=nfs:192.168.1.1:/pxe/rhas4u6

Additional information

This is caused by a resource conflict when both, the BIOS and the operating system, try to initiate UART (SIO) at the same time.

The user can use the C.R. function after POST (like DOS), but the user cannot see any information during GRUB. It is not an issue for the user, in the operating system, if the operating system has enabled the C.R. function.

Document Location

Worldwide

Operating System

System x:Operating system independent / None

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Document Information

Modified date:
29 January 2019

UID

ibm1MIGR-5076153

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