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    SubjectRe: v4.17 regression: PowerMac G3 won't boot, was Re: [PATCH v5 1/3] of: cache phandle nodes to reduce cost of of_find_node_by_phandle()
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    Hi Finn,

    On 08/29/18 17:44, Finn Thain wrote:
    > Hi Frank,
    >
    > Linux v4.17 and later will no longer boot on a G3 PowerMac. The boot hangs
    > very early, before any video driver loads.
    >
    > Stan and I were able to bisect the regression between v4.16 and v4.17 and
    > arrived at commit 0b3ce78e90fc ("of: cache phandle nodes to reduce cost of
    > of_find_node_by_phandle()").
    >
    > I don't see any obvious bug in 0b3ce78e90fc or b9952b5218ad. But if you
    > revert these from v4.18 (which is also affected) that certainly resolves
    > the issue.
    >
    > I did see this in the kernel messages:
    >
    > Duplicate name in PowerPC,750, renamed to "l2-cache#1"
    > Duplicate name in mac-io, renamed to "ide#1"
    > Duplicate name in ide#1, renamed to "atapi-disk#1"
    > Duplicate name in multifunc-device, renamed to "pci1799,1#1"
    >
    > No idea whether that's relevant; I haven't done any further investigation.
    > Complete dmesg output is attached. Please let me know if there's any more
    > information you need to help find the bug.
    >
    > Thanks.

    I don't have any useful answers yet, but I am following the thread and have
    also quickly scanned the two commits for any obvious cause. I will look
    into this some more, but have a few other tasks that I need to complete
    first.

    A long shot, but something to consider, is that I failed to cover the
    cases of dynamic devicetree updates (removing nodes that contain a
    phandle) in ways other than overlays. Michael Ellerman has reported
    such a problem for powerpc/mobility with of_detach_node(). A patch to
    fix that is one of the tasks I need to complete.

    -Frank

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