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    SubjectRe: PROBLEM: 4.15.0-rc3 APIC causes lockups on Core 2 Duo laptop
    On Thu, Dec 28, 2017 at 06:30:58PM -0500, Alexandru Chirvasitu wrote:
    > Attached, but heads up on this: when redirecting the output of lspci
    > -vvv to a text file as root I get
    >
    > pcilib: sysfs_read_vpd: read failed: Input/output error
    >
    > I can find bugs filed for various distros to this same effect, but
    > haven't tracked down any explanations.

    This is a tangent, but I think you should *always* see "Input/output
    error" on this system when running "lspci -vvv" as root, regardless of
    whether you redirect the output (the error probably goes to stderr,
    not stdout, so it's probably easy to miss when not redirecting the
    output).

    I think this is the -EIO return from pci_vpd_read(), which probably
    means pci_vpd_size() returned 0 for one of your devices, which means
    the VPD data provided by the device wasn't formatted correctly. If
    this happens, you should see a warning in dmesg about it ("invalid VPD
    tag" or similar) -- could you verify that?

    It's possible we should return something other than -EIO, or maybe
    pcilib should do something other than emitting the warning. In
    pcilib, sysfs_read_vpd() emits the warning [1], and it would seem sort
    of ugly to special-case EIO, so maybe we should change this in the
    kernel.

    It looks like your Qualcomm Atheros Attansic NIC at 06:00.0 is the
    only device with VPD, so that's probably the one:

    06:00.0 Ethernet controller: Qualcomm Atheros Attansic L2 Fast Ethernet
    Capabilities: [6c] Vital Product Data
    Not readable

    I think lspci would still print "Not readable" if we just made the
    kernel return 0 instead of -EIO [2].

    Bjorn

    [1] https://git.kernel.org/pub/scm/utils/pciutils/pciutils.git/tree/lib/sysfs.c#n410
    [2] https://git.kernel.org/pub/scm/utils/pciutils/pciutils.git/tree/ls-vpd.c#n87

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