Date: Thu, 1 May 2014 14:24:31 -0400 From: John Baldwin <jhb@freebsd.org> To: Don Lewis <truckman@freebsd.org> Cc: stable@freebsd.org Subject: Re: Thinkpad R60 hangs when booting recent 8.4-STABLE Message-ID: <201405011424.31981.jhb@freebsd.org> In-Reply-To: <201404302245.s3UMj2UL033567@gw.catspoiler.org> References: <201404302245.s3UMj2UL033567@gw.catspoiler.org>
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On Wednesday, April 30, 2014 6:45:02 pm Don Lewis wrote: > On 30 Apr, John Baldwin wrote: > > On Wednesday, April 30, 2014 1:30:01 pm Don Lewis wrote: > >> On 30 Apr, John Baldwin wrote: > >> > On Tuesday, April 29, 2014 9:17:19 pm Don Lewis wrote: > >> >> On 29 Apr, John Baldwin wrote: > >> >> > On Monday, April 28, 2014 8:56:03 pm Don Lewis wrote: > >> >> > >> >> I just took a closer look at the dmesg output from the two kernels. > >> >> > >> >> >> agp0: <Intel 82855 host to AGP bridge> on hostb0 > >> >> >> hostb0: Reserved 0x10000000 bytes for rid 0x10 type 3 at 0xd0000000 > >> >> > >> >> The above line is different with the r262226 kernel: > >> >> hostb0: Reserved 0x10000000 bytes for rid 0x10 type 3 at 0 > >> > > >> > Yes, a resource at 0 is going to break things. 9.2 has the NEW_PCIB > > option > >> > enabled. You can try enabling that for 8.4 to see if it fixes this issue. > >> > If it does, it narrows down where to look for the bug. > >> > >> It behaves the same way with NEW_PCIB. I see hostb at 0 and then the > >> hang shortly thereafter. > > > > Ok. hostb isn't actually behind a bridge so that probably makes sense. The > > one other reporter who sent me debug output had a BAR on his vgapci0 device > > that ended up being at 0 as well (and an active BAR at 0 is pretty much > > guaranteed to hose a box). > > > > Are you up for doing some printf sleuthing? There are two odd things that I > > see so far: > > Yup, I've already started down that path. > > > 1) the base address of 0. The question here is if pci_add_map() in > > sys/dev/pci/pci.c decides to set start to 0 explicitly, or if it happens > > further up the callchain (should be bus_alloc_resource calls in > > sys/dev/acpica/acpi_pcib_acpi.c, sys/x86/x86/nexus.c and then in the > > rman code itself in sys/kern/subr_rman.c) > > > > 2) The 'reserved' printfs during boot probe. Those come from a printf in > > pci_alloc_resource() in sys/dev/pci/pci.c. However, that should not be called > > until a driver attaches to a device and calls bus_alloc_resource(). It should > > not be called from pci_add_child() as it seems to be now. > > What I know so far is that for hostb0, pci_alloc_resource() is being > called with start=0x0 and end=0xffffffff, resource_list_find() is > succeeding, we don't call pci_alloc_map(), and rman_get_start(rle->res) > is returning 0. I don't see a call for pci_add_map() for hostb0 unless > it is much earlier and scrolled off the screen. The call to pci_add_map() is earlier. It is called from pci_add_child() when we scan the PCI bus during attach of the PCI bus device itself. In theory, pci_alloc_resource() should not be called until a driver actually attaches to the device and calls bus_alloc_resource() from its probe or attach routine. > For debugging #2, should I back out r262226 so that the machine boots > and I can capture the full dmesg buffer? Yes. I think you could just add a panic at that printf line and get a backtrace for now as a first step as it is occurring way too early. -- John Baldwin
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