path: root/Documentation/x86/usb-legacy-support.txt
diff options
Diffstat (limited to 'Documentation/x86/usb-legacy-support.txt')
1 files changed, 0 insertions, 44 deletions
diff --git a/Documentation/x86/usb-legacy-support.txt b/Documentation/x86/usb-legacy-support.txt
deleted file mode 100644
index 1894cdf..0000000
--- a/Documentation/x86/usb-legacy-support.txt
+++ /dev/null
@@ -1,44 +0,0 @@
-USB Legacy support
-Vojtech Pavlik <>, January 2004
-Also known as "USB Keyboard" or "USB Mouse support" in the BIOS Setup is a
-feature that allows one to use the USB mouse and keyboard as if they were
-their classic PS/2 counterparts. This means one can use an USB keyboard to
-type in LILO for example.
-It has several drawbacks, though:
-1) On some machines, the emulated PS/2 mouse takes over even when no USB
- mouse is present and a real PS/2 mouse is present. In that case the extra
- features (wheel, extra buttons, touchpad mode) of the real PS/2 mouse may
- not be available.
-2) If CONFIG_HIGHMEM64G is enabled, the PS/2 mouse emulation can cause
- system crashes, because the SMM BIOS is not expecting to be in PAE mode.
- The Intel E7505 is a typical machine where this happens.
-3) If AMD64 64-bit mode is enabled, again system crashes often happen,
- because the SMM BIOS isn't expecting the CPU to be in 64-bit mode. The
- BIOS manufacturers only test with Windows, and Windows doesn't do 64-bit
- yet.
-Problem 1) can be solved by loading the USB drivers prior to loading the
-PS/2 mouse driver. Since the PS/2 mouse driver is in 2.6 compiled into
-the kernel unconditionally, this means the USB drivers need to be
-compiled-in, too.
-Problem 2) can currently only be solved by either disabling HIGHMEM64G
-in the kernel config or USB Legacy support in the BIOS. A BIOS update
-could help, but so far no such update exists.
-Problem 3) is usually fixed by a BIOS update. Check the board
-manufacturers web site. If an update is not available, disable USB
-Legacy support in the BIOS. If this alone doesn't help, try also adding
-idle=poll on the kernel command line. The BIOS may be entering the SMM
-on the HLT instruction as well.