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SubjectRE: Info: mapping multiple BARs. Your kernel is fine.
Date


> -----Original Message-----
> From: Lu, Aaron
> Sent: Thursday, March 20, 2014 10:24 AM
> To: Rafael J. Wysocki; Borislav Petkov
> Cc: lkml; x86@kernel.org; Bjorn Helgaas; Linux PCI; ACPI Devel Maling
> List; Zhang, Rui; Yinghai Lu; H. Peter Anvin; Stephane Eranian
> Subject: Re: Info: mapping multiple BARs. Your kernel is fine.
> Importance: High
>
> On 03/15/2014 10:15 PM, Rafael J. Wysocki wrote:
> > [CC list rearranged]
> >
> > On Monday, February 24, 2014 05:24:00 PM Borislav Petkov wrote:
> >> This started happening this morning after booting -rc4+tip, let's
> add
> >> *everybody* to CC :-)
> >>
> >> We have intel_uncore_init, snb_uncore_imc_init_box, uncore_pci_probe
> >> and other goodies on the stack.
> >
> > I've just gone throught this.
> >
> > So the problem is that we have the PNP "system" driver whose only
> > purpose seems to be to reserve system resources so that the PCI layer
> > doesn't assign them to new devices on hotplug (disclaimer: I didn't
> > invent it, I only read the code and comments in there).
>
> And to PCI devices which have uninitialized BARs.
>
> >
> > It does that for ACPI device objects having the "PNP0C02" and
> "PNP0C01" IDs.
> >
> > Apparently, snb_uncore_imc_init_box() steps on a range already
> > reserved by that driver on your box. And this doesn't seem to be a
> > coincidence, because the ACPI device object in question probably
> > *does* correspond to the memory controller that the uncore driver
> attempts to use.
> >
> > I'm not sure how to address that right now to be honest. Arguably,
> > the PNP "system" driver should be replaced with something saner, but
> > still the resources it claims need to be kept out of reach of the
> > PCI's resource allocation code.
>
> The quirk_system_pci_resources is meant to disable PNP devices'
> resource if they collide with any known PCI device's BAR. I'm not sure
> why it doesn't work here, perhaps the uncore PCI device doesn't have a
> BAR that falls in the PNP device's resource window?
>
I've talked with Yan Zheng, and I was told that this resource "0xfed10000 - 0xfed15fff"
is got from PCI device register directly, which is not in its BAR range.
Thus IMO, it is impossible for PNP layer to be aware of this resource.

BTW, about drivers/pnp/system.c, if its ONLY purpose is to prevent those
resources from being allocated to uninitialized PCI devices, then IMO,
the best way to do this is make PCI bus handle those PNP0C01/PNP0C02
resources directly, probably via a platform callback, say,
1. make drivers/pnp/system.c a no-op for PNPACPI, by checking pnp_dev->protocol.
2. introduce acpi_check_reserved_resource() to parsing PNP0C01/PNP0C02 resources.
3. in PCI bus, invoke acpi_check_reserved_resource() when assigning
resources to PCI devices.

Thanks,
rui

> Thanks,
> Aaron
>
> >
> >> ...
> >> [ 0.488998] software IO TLB [mem 0xcac30000-0xcec30000] (64MB)
> mapped at [ffff8800cac30000-ffff8800cec2ffff]
> >> [ 0.489975] resource map sanity check conflict: 0xfed10000
> 0xfed15fff 0xfed10000 0xfed13fff pnp 00:01
> >> [ 0.490079] ------------[ cut here ]------------
> >> [ 0.490204] WARNING: CPU: 2 PID: 1 at arch/x86/mm/ioremap.c:171
> __ioremap_caller+0x372/0x380()
> >> [ 0.490306] Info: mapping multiple BARs. Your kernel is fine.
> >> [ 0.490371] Modules linked in:
> >> [ 0.490558] CPU: 2 PID: 1 Comm: swapper/0 Not tainted 3.14.0-rc4+
> #1
> >> [ 0.490642] Hardware name: LENOVO 2320CTO/2320CTO, BIOS G2ET86WW
> (2.06 ) 11/13/2012
> >> [ 0.490742] 00000000000000ab ffff880213d01ad8 ffffffff816112e3
> 0000000000000006
> >> [ 0.491032] ffff880213d01b28 ffff880213d01b18 ffffffff8104e9bc
> ffff880213d01b08
> >> [ 0.491343] ffffc90000c58000 00000000fed10000 00000000fed10000
> 0000000000006000
> >> [ 0.491631] Call Trace:
> >> [ 0.493337] [<ffffffff816112e3>] dump_stack+0x4f/0x7c
> >> [ 0.493420] [<ffffffff8104e9bc>] warn_slowpath_common+0x8c/0xc0
> >> [ 0.493503] [<ffffffff8104eaa6>] warn_slowpath_fmt+0x46/0x50
> >> [ 0.493588] [<ffffffff8103f1e2>] __ioremap_caller+0x372/0x380
> >> [ 0.493674] [<ffffffff810211a2>] ?
> snb_uncore_imc_init_box+0x62/0x90
> >> [ 0.493761] [<ffffffff8103f247>] ioremap_nocache+0x17/0x20
> >> [ 0.493846] [<ffffffff810211a2>]
> snb_uncore_imc_init_box+0x62/0x90
> >> [ 0.493933] [<ffffffff81022925>] uncore_pci_probe+0xe5/0x1e0
> >> [ 0.494020] [<ffffffff812d487e>] local_pci_probe+0x4e/0xa0
> >> [ 0.494104] [<ffffffff81418a59>] ? get_device+0x19/0x20
> >> [ 0.494213] [<ffffffff812d5cd1>] pci_device_probe+0xe1/0x130
> >> [ 0.494300] [<ffffffff8141d3cb>] driver_probe_device+0x7b/0x240
> >> [ 0.494385] [<ffffffff8141d63b>] __driver_attach+0xab/0xb0
> >> [ 0.494469] [<ffffffff8141d590>] ?
> driver_probe_device+0x240/0x240
> >> [ 0.494551] [<ffffffff8141b71e>] bus_for_each_dev+0x5e/0x90
> >> [ 0.494634] [<ffffffff8141cede>] driver_attach+0x1e/0x20
> >> [ 0.494718] [<ffffffff8141ca57>] bus_add_driver+0x117/0x230
> >> [ 0.494802] [<ffffffff8141dd34>] driver_register+0x64/0xf0
> >> [ 0.494884] [<ffffffff812d4c14>] __pci_register_driver+0x64/0x70
> >> [ 0.494972] [<ffffffff81d0319b>] ? uncore_types_init+0x19c/0x19c
> >> [ 0.495056] [<ffffffff81d03312>] intel_uncore_init+0x177/0x41c
> >> [ 0.495155] [<ffffffff81d0319b>] ? uncore_types_init+0x19c/0x19c
> >> [ 0.495242] [<ffffffff8100029e>] do_one_initcall+0x4e/0x170
> >> [ 0.495326] [<ffffffff81071100>] ? parse_args+0x60/0x360
> >> [ 0.495411] [<ffffffff81cfbfb8>]
> kernel_init_freeable+0x106/0x19a
> >> [ 0.495497] [<ffffffff81cfb83b>] ? do_early_param+0x86/0x86
> >> [ 0.495582] [<ffffffff81607ef0>] ? rest_init+0xd0/0xd0
> >> [ 0.495666] [<ffffffff81607efe>] kernel_init+0xe/0xf0
> >> [ 0.495749] [<ffffffff81621f6c>] ret_from_fork+0x7c/0xb0
> >> [ 0.495831] [<ffffffff81607ef0>] ? rest_init+0xd0/0xd0
> >> [ 0.495921] ---[ end trace 428f365c054d9a01 ]---
> >> [ 0.496196] RAPL PMU detected, hw unit 2^-16 Joules, API unit is
> 2^-32 Joules, 3 fixed counters 163840 ms ovfl timer
> >> [ 0.498598] futex hash table entries: 1024 (order: 5, 131072
> bytes)
> >> [ 0.498833] audit: initializing netlink subsys (disabled)
> >> [ 0.499024] audit: type=2000 audit(1393259866.477:1): initialized
> >> ...
> >>
> >>
> >

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