Add the rt linux 4.1.3-rt3 as base

Import the rt linux 4.1.3-rt3 as OPNFV kvm base.

It's from git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git linux-4.1.y-rt and
the base is:

commit 0917f823c59692d751951bf5ea699a2d1e2f26a2
Author: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date:   Sat Jul 25 12:13:34 2015 +0200

    Prepare v4.1.3-rt3

    Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

We lose all the git history this way and it's not good. We
should apply another opnfv project repo in future.

Change-Id: I87543d81c9df70d99c5001fbdf646b202c19f423
Signed-off-by: Yunhong Jiang <yunhong.jiang@intel.com>

1 files changed, 44 insertions, 0 deletions

diff --git a/kernel/Documentation/x86/usb-legacy-support.txt b/kernel/Documentation/x86/usb-legacy-support.txt
new file mode 100644
index 000000000..1894cdfc6
--- /dev/null
+++ b/kernel/Documentation/x86/usb-legacy-support.txt
@@ -0,0 +1,44 @@
+USB Legacy support
+~~~~~~~~~~~~~~~~~~
+
+Vojtech Pavlik <vojtech@suse.cz>, 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.
+
+Solutions:
+
+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.
+