Thinkpad R60 hangs when booting recent 8.4-STABLE

[Don Lewis]

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.

For debugging #2, should I back out r262226 so that the machine boots
and I can capture the full dmesg buffer?