1
2 .. SPDX-License-Identifier: GPL-2.0
3
4 ==================
5 USB Legacy support
6 ==================
7
8 :Author: Vojtech Pavlik <vojtech@suse.cz>, Janu
9
10
11 Also known as "USB Keyboard" or "USB Mouse sup
12 feature that allows one to use the USB mouse a
13 their classic PS/2 counterparts. This means o
14 type in LILO for example.
15
16 It has several drawbacks, though:
17
18 1) On some machines, the emulated PS/2 mouse t
19 mouse is present and a real PS/2 mouse is p
20 features (wheel, extra buttons, touchpad mo
21 not be available.
22
23 2) If CONFIG_HIGHMEM64G is enabled, the PS/2 m
24 system crashes, because the SMM BIOS is not
25 The Intel E7505 is a typical machine where
26
27 3) If AMD64 64-bit mode is enabled, again syst
28 because the SMM BIOS isn't expecting the CP
29 BIOS manufacturers only test with Windows,
30 yet.
31
32 Solutions:
33
34 Problem 1)
35 can be solved by loading the USB drivers pri
36 PS/2 mouse driver. Since the PS/2 mouse driv
37 the kernel unconditionally, this means the U
38 compiled-in, too.
39
40 Problem 2)
41 can currently only be solved by either disab
42 in the kernel config or USB Legacy support i
43 could help, but so far no such update exists
44
45 Problem 3)
46 is usually fixed by a BIOS update. Check the
47 manufacturers web site. If an update is not
48 Legacy support in the BIOS. If this alone do
49 idle=poll on the kernel command line. The BI
50 on the HLT instruction as well.
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