Root/
1 | USB Legacy support |
2 | ~~~~~~~~~~~~~~~~~~ |
3 | |
4 | Vojtech Pavlik <vojtech@suse.cz>, January 2004 |
5 | |
6 | |
7 | Also known as "USB Keyboard" or "USB Mouse support" in the BIOS Setup is a |
8 | feature that allows one to use the USB mouse and keyboard as if they were |
9 | their classic PS/2 counterparts. This means one can use an USB keyboard to |
10 | type in LILO for example. |
11 | |
12 | It has several drawbacks, though: |
13 | |
14 | 1) On some machines, the emulated PS/2 mouse takes over even when no USB |
15 | mouse is present and a real PS/2 mouse is present. In that case the extra |
16 | features (wheel, extra buttons, touchpad mode) of the real PS/2 mouse may |
17 | not be available. |
18 | |
19 | 2) If CONFIG_HIGHMEM64G is enabled, the PS/2 mouse emulation can cause |
20 | system crashes, because the SMM BIOS is not expecting to be in PAE mode. |
21 | The Intel E7505 is a typical machine where this happens. |
22 | |
23 | 3) If AMD64 64-bit mode is enabled, again system crashes often happen, |
24 | because the SMM BIOS isn't expecting the CPU to be in 64-bit mode. The |
25 | BIOS manufacturers only test with Windows, and Windows doesn't do 64-bit |
26 | yet. |
27 | |
28 | Solutions: |
29 | |
30 | Problem 1) can be solved by loading the USB drivers prior to loading the |
31 | PS/2 mouse driver. Since the PS/2 mouse driver is in 2.6 compiled into |
32 | the kernel unconditionally, this means the USB drivers need to be |
33 | compiled-in, too. |
34 | |
35 | Problem 2) can currently only be solved by either disabling HIGHMEM64G |
36 | in the kernel config or USB Legacy support in the BIOS. A BIOS update |
37 | could help, but so far no such update exists. |
38 | |
39 | Problem 3) is usually fixed by a BIOS update. Check the board |
40 | manufacturers web site. If an update is not available, disable USB |
41 | Legacy support in the BIOS. If this alone doesn't help, try also adding |
42 | idle=poll on the kernel command line. The BIOS may be entering the SMM |
43 | on the HLT instruction as well. |
44 | |
45 |
Branches:
ben-wpan
ben-wpan-stefan
javiroman/ks7010
jz-2.6.34
jz-2.6.34-rc5
jz-2.6.34-rc6
jz-2.6.34-rc7
jz-2.6.35
jz-2.6.36
jz-2.6.37
jz-2.6.38
jz-2.6.39
jz-3.0
jz-3.1
jz-3.11
jz-3.12
jz-3.13
jz-3.15
jz-3.16
jz-3.18-dt
jz-3.2
jz-3.3
jz-3.4
jz-3.5
jz-3.6
jz-3.6-rc2-pwm
jz-3.9
jz-3.9-clk
jz-3.9-rc8
jz47xx
jz47xx-2.6.38
master
Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
v2.6.34-rc7
v3.9