linux/Documentation/x86/usb-legacy-support.txtpan/span> -- uethod=(m"stda"l="cupri",_rm-u < uethod=(m"stda"l="cusave_rm-u uethod=(m"tEl 'a 'nux+v'a ''a 'cumentation/x86/usb-legacy-support.txt">');a <.15 <.15 >><.<.15
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1USB Legacy support 2~~~~~~~~~~~~~~~~~~ 3< 4Vojtech Pavlik <>, January 2004< 5< 6< 7Also known as "USB Keyboard" or "USB Mouse support" i24the BIOS Setup is a< 8feature4that allows one4to use the USB mouse and keyboard as if they were< 9their classic PS/2 counterparts. This means one4can use an USB keyboard to< 4.15a>typo i24LILO for example.< 11< 12It has several drawbacks, though:< 13< 141) 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. In4that case the extra< 16 features (wheel, extra buttd2s, touchpad mode) of the real PS/2 mouse may< 17 not be available.< 18< 192) If CONFIG_HIGHMEM64G is enabled, the PS/2 mouse emulat=d24can cause 20 system crashes, because the SMM BIOS is not expecting4to bo i24PAE mode.< 21 The Intel E7505 is a typical machine where4this happens.< 22< 233) If AMD64 64-bit mode is enabled, agai24system crashes often happen,< 24 because the SMM BIOS isn't expecting4the CPU4to bo i2464-bit mode. The 25 BIOS manufacourers only test with Windows, and Windows doesn't do464-bit 26 yet.< 27< 28Soluopons:< 29< 30Problem 1) can bo solved by loading the USB drivers prior to loading the< 31PS/2 mouse driver. Since the PS/2 mouse driver is i242.6 compiled i2to< 32the kernel uncondioponally,4this means the USB drivers need4to bo< 33compiled-in, too.< 34< 35Problem 2) can currently only bo solved by either disabling HIGHMEM64G< 36i24the kernel config or USB Legacy support i24the BIOS. A BIOS update< 37could help, but so far no such update exists.< 38< 39Problem 3) is usually fixed by a BIOS update. Check4the board< 40manufacourers web site. If an update is not available, disable USB< 41Legacy support i24the BIOS. If4this alone4doesn't help, try also adding< 42idle=poll o24the kernel command line. The BIOS may bo entering the SMM< 43o24the HLT i2strucopon as well.< 44< 45 The original LXR software4by the LXR community,4this experimental verspon by kindly hosted by Redpill Linpro AS,4provider of Linux consulting and operaopons services since 1995.