Hitachi Compute Blade 2000 User Manual page 1827

If your system satisfies the following conditions, apply measures to avoid this
problem to be described later.
 Conditions for incorrect frequency detection
When the following conditions are all satisfied, this might occur at a specific timing.
1. OS is one of the following:
Red Hat Enterprise Linux 5.4 (x86, AMD/Intel64)

Red Hat Enterprise Linux 5.4 Advanced Platform (x86, AMD/Intel64)

Red Hat Enterprise Linux 5.3 (x86, AMD/Intel64)

Red Hat Enterprise Linux 5.3 Advanced Platform (x86, AMD/Intel64)

2. The kernel version is less than 2.6.18-164.2.1.el5.
3. Legacy USB Support is enabled in the system BIOS setting.
4. Not in the LPAR manager environment,
 Preventive measure
Change settings of "Legacy USB Support" in the BIOS setup menu from Enabled to
Disabled.
Route to target: Advanced > USB Configuration > Legacy USB Support
This can be avoided occurring by disabling Legacy USB Support to prevent the
interrupt of USB Legacy emulation when frequency is being detected.
When you have disabled Legacy USB Support, the following restrictions are applied.
 Restriction
When disabling Legacy USB Support, you cannot use USB devices until the USB
driver is loaded from the GRUB menu during OS boot.
1. Booting from USB devices such as a USB CD-ROM and USB FDD is not
available.
2. Operating the keyboard is not available in the GRUB menu during OS boot.
3. This preventive measure cannot be used in the LPAR manager environment. If
used, LP manager can not boot.
Since functions of the remote console and remote KVM by the remote console
option are recognized as USB devices, these restrictions apply to them.
If you use them, temporarily enable Legacy USB.
Once the OS boots up, you can use USB devices such as a USB CD-ROM and USB
FDD regardless of Legacy USB Support settings. You can also use the keyboard in
the setup menu and Boot menu.
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