Date: Tue, 20 Jul 2004 13:43:44 +0100 From: Ian Dowse <iedowse@maths.tcd.ie> To: "M. Warner Losh" <imp@bsdimp.com> Cc: pjd@freebsd.org Subject: Re: Unloading USB driver while device is attached. Message-ID: <200407201343.aa92531@salmon.maths.tcd.ie> In-Reply-To: Your message of "Mon, 19 Jul 2004 19:50:56 MDT." <20040719.195056.35662742.imp@bsdimp.com>
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In message <20040719.195056.35662742.imp@bsdimp.com>, "M. Warner Losh" writes: >: o Attempt to follow the correct procedure for synchronising with >: the BIOS via SMM to take over control of the EHCI controller. >: This may fix problems when the BIOS is configured to emulate >: legacy devices, but is untested on any affected machines. > >Docs on how to do this? I've not seen this info... It's in the EHCI spec at: http://developer.intel.com/technology/usb/download/ehci-r10.pdf See sections 5.1 (EHCI Extended Capability: Pre-OS to OS Handoff Synchronization) and 2.1.7 (USBLEGSUP - USB Legacy Support Extended Capability). A quick summary is that if the BIOS implements legacy emulation via SMIs then there is a particular host controller flag that the OS is supposed to set that will cause the BIOS to receive an SMI. The BIOS should recognise this signal and disable the legacy support, giving the OS exclusive access to the host controller. Ian
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