Date: Mon, 27 Oct 2008 11:57:05 -0400 From: John Baldwin <jhb@freebsd.org> To: Jeremy Chadwick <koitsu@freebsd.org> Cc: Jo Rhett <jrhett@netconsonance.com>, Aragon Gouveia <aragon@phat.za.net>, freebsd-stable Stable <freebsd-stable@freebsd.org> Subject: Re: 6.4 RC1 locks up solid on first reboot Message-ID: <200810271157.06096.jhb@freebsd.org> In-Reply-To: <20081025080945.GA55413@icarus.home.lan> References: <A5A9A4D4-CD16-45FA-A2AC-62C4B5AE976D@netconsonance.com> <20081025014218.GA47549@phat.za.net> <20081025080945.GA55413@icarus.home.lan>
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On Saturday 25 October 2008 04:09:45 am Jeremy Chadwick wrote: > Just for posterity: the USB Legacy Support BIOS option does not affect > natively-connected PS/2 keyboards; you can leave the option enabled even > in the scenario where you have a USB keyboard *and* a PS/2 keyboard > plugged in; one will not "trump" the other. Instead, you should have > two keyboards which function in OSes/environments which lack a USB > stack. (That is, until something resets/reassigns the BIOS-controlled > interrupt, which will then break USB->PS/2 emulation; the native PS/2 > keyboard should not be affected by this) This last statement is not quite true (at least not always true). For many systems, the way the PS/2 emulation works is that accesses to the backing I/O ports (0x60 and 0x64) case a trap into SMM and the SMI handler in the BIOS then talks to the USB controller and keyboard and updates the register values to simulate the I/O port accesses. This is disabled by having the USB host controller driver frob flags in controller registers to disable the SMI traps. -- John Baldwin
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