Kontron pITX-SP - Manual (Page 57)

KTD-S0003-C Page 53 Linux Support
p ITX-SP Software Guide
12.3 Reboot Problem
Most Linux distributions will freeze after a restart or a shutdown command is issued right at the very end of
the process forcing the system to do a hard reset. By default the Linux kernel uses the
reboot=kbd method
i.e. it tries to look for a keyboard controller and issue a reset/shutdown command to it. The pITX-SP board
doesn’t have a keyboard controller and a fix is required.
The reboot behavior can be corrected within the BIOS Setup through the entry
Advanced/Onboard Device
Configuration/Chipset Configuration/Linux Reboot Fix. When this entry is set to Enabled a small part of
the port 64h access is emulated. This is not a complete emulation of the keyboard controller which means
that side effects might occure. The following table shows a small overview about system behavior of dif-
ferent linux systems:
Distribution Result
Fedora ®
✔
Suse ®
Long timeout during start up
Ubuntu ®
✔
As an alternative solution other reboot methods can be used within Linux operating systems.
In order to solve the problem you should append the following parameter to the kernel in the form of
reboot=<parameter> at the time of boot (possible a keystroke is necessary):
reboot = acpi use the RESET_REG in the FADT
reboot = pci use the PCI reset register 0xCF9
Once your system boots you can verify whether the parameter was correctly passed or not with the fol-
lowing command:
cat /proc/cmdline
Result (example):
root = ... reboot = bios
You can find the list of all the above parameters in the reboot.c file in the Linux kernel source. When the
GRUB bootloader is used the reboot command can be entered into the file /boot/grub/grub.conf.