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Date:      Tue, 23 Dec 2008 18:33:22 +0100
From:      Andre Albsmeier <Andre.Albsmeier@siemens.com>
To:        Andre Albsmeier <Andre.Albsmeier@siemens.com>
Cc:        freebsd-hackers@freebsd.org
Subject:   Re: How to "detach" a foreign driver from a device so my driver can attach?
Message-ID:  <20081223173322.GA4123@curry.mchp.siemens.de>
In-Reply-To: <20081216230430.GA24352@curry.mchp.siemens.de>
References:  <20081216230430.GA24352@curry.mchp.siemens.de>

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On Wed, 17-Dec-2008 at 00:04:30 +0100, Andre Albsmeier wrote:
> Hello all,
> 
> I am writing a driver which attaches to the Host-PCI bridge. When
> compiled into the kernel or loaded by the loader everything works
> and the driver gets attached. This is due to the fact that I return
> BUS_PROBE_SPECIFIC in my probe routine which gains over the -10000
> returned by pci_hostb_probe() in i386/pci/pci_bus.c.
> 
> However, when I want to load my driver via kldload this fails since
> the hostb device has already been attached during kernel load (when
> my driver was not present):
> 
> hostb0@pci0:0:0:    class=0x060000 card=0x11d510cf chip=0x35808086 rev=0x02 hdr=0x00
> 
> What can I do to make my driver load via kldload?
> Is there a way to detach the hostb0 from the Host-PCI bridge?

Found the answer myself but will post it here in case anyone
got a similar problem one day: I added the device detach method
for the hostb driver to sys/i386/pci/pci_bus.c:

--- sys/i386/pci/pci_bus.c.ORI	2007-08-17 08:12:33.000000000 +0200
+++ sys/i386/pci/pci_bus.c	2008-12-23 13:34:35.000000000 +0100
@@ -619,10 +619,13 @@
 	return 0;
 }
 
+static int pci_hostb_detach(device_t dev) { return 0; }
+
 static device_method_t pci_hostb_methods[] = {
 	/* Device interface */
 	DEVMETHOD(device_probe,		pci_hostb_probe),
 	DEVMETHOD(device_attach,	pci_hostb_attach),
+	DEVMETHOD(device_detach,	pci_hostb_detach),
 	DEVMETHOD(device_shutdown,	bus_generic_shutdown),
 	DEVMETHOD(device_suspend,	bus_generic_suspend),
 	DEVMETHOD(device_resume,	bus_generic_resume),

Now, when kldload'ing my driver, it can walk through all devices
and detach hostb using device_detach().

	-Andre



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