Greg Kroah-Hartman
598cf27219
Link: https://lore.kernel.org/r/20260217200002.683975158@linuxfoundation.org Tested-by: Florian Fainelli <florian.fainelli@broadcom.com> Tested-by: Takeshi Ogasawara <takeshi.ogasawara@futuring-girl.com> Tested-by: Peter Schneider <pschneider1968@googlemail.com> Tested-by: Jon Hunter <jonathanh@nvidia.com> Tested-by: Salvatore Bonaccorso <carnil@debian.org> Tested-by: Brett A C Sheffield <bacs@librecast.net> Tested-by: Mark Brown <broonie@kernel.org> Tested-by: Luna Jernberg <droidbittin@gmail.com> Tested-by: Ronald Warsow <rwarsow@gmx.de> Tested-by: Justin M. Forbes <jforbes@fedoraproject.org> Tested-by: Ron Economos <re@w6rz.net> Tested-by: Miguel Ojeda <ojeda@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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42 lines
1.5 KiB
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.. SPDX-License-Identifier: GPL-2.0
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==================
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USB Legacy support
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==================
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:Author: Vojtech Pavlik <vojtech@suse.cz>, January 2004
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Also known as "USB Keyboard" or "USB Mouse support" in the BIOS Setup is a
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feature that allows one to use the USB mouse and keyboard as if they were
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their classic PS/2 counterparts. This means one can use an USB keyboard to
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type in LILO for example.
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It has several drawbacks, though:
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1) On some machines, the emulated PS/2 mouse takes over even when no USB
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mouse is present and a real PS/2 mouse is present. In that case the extra
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features (wheel, extra buttons, touchpad mode) of the real PS/2 mouse may
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not be available.
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2) If AMD64 64-bit mode is enabled, again system crashes often happen,
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because the SMM BIOS isn't expecting the CPU to be in 64-bit mode. The
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BIOS manufacturers only test with Windows, and Windows doesn't do 64-bit
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yet.
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Solutions:
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Problem 1)
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can be solved by loading the USB drivers prior to loading the
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PS/2 mouse driver. Since the PS/2 mouse driver is in 2.6 compiled into
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the kernel unconditionally, this means the USB drivers need to be
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compiled-in, too.
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Problem 2)
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is usually fixed by a BIOS update. Check the board
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manufacturers web site. If an update is not available, disable USB
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Legacy support in the BIOS. If this alone doesn't help, try also adding
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idle=poll on the kernel command line. The BIOS may be entering the SMM
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on the HLT instruction as well.
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