Date: Tue, 16 Aug 2011 15:09:09 -0400 From: John Baldwin <jhb@freebsd.org> To: Andriy Gapon <avg@freebsd.org> Cc: "freebsd-current@freebsd.org" <freebsd-current@freebsd.org>, David Somayajulu <david.somayajulu@qlogic.com> Subject: Re: Loading drivers via kldload Message-ID: <201108161509.09939.jhb@freebsd.org> In-Reply-To: <4E4A9A23.7060807@FreeBSD.org> References: <75E1A2A7D185F841A975979B0906BBA67BCC877062@AVEXMB1.qlogic.org> <201108161145.02733.jhb@freebsd.org> <4E4A9A23.7060807@FreeBSD.org>
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On Tuesday, August 16, 2011 12:26:11 pm Andriy Gapon wrote: > > The following are pure speculations, I'd rather let David speak, but just in case; > > on 16/08/2011 18:45 John Baldwin said the following: > > Well, that would seem odd, still. It only returns BUS_PROBE_GENERIC (not 0), so > > David's driver's probe routine should still be called to get a chance to attach to > > the device. > > Maybe it doesn't do that exactly because device and vendor ID are zeroes as David > described earlier. Eh? device_probe_and_attach()'s loop to probe drivers is not PCI-specific, it has no idea if a given device is PCI device or not let alone if it has non-zero subvendor IDs. Also, ata_pci_probe() doesn't look at the subvendor IDs at all. > > Also, the ATA driver only allocates its BAR once, so it shouldn't > > trigger the panic in question in that case (the panic is only triggered when you > > try to double-allocate a BAR). > > This makes only if the BAR has sane values. Not sure what happens if the BAR has > some junk that duplicates other PCI device, or something like that. The panic in question is due to a resource that was reserved by the parent bus (i.e. either ACPI or PCI) using resource_list_reserve(), then a driver called resource_list_alloc() on it once successfully, and resource_list_alloc() is being called a second time to allocate an already- allocated resource. That won't happen due to junk in a BAR (and BARs are all standard config header registers anyway). -- John Baldwin
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