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SubjectRe: Kernel regression introduced by "e1000e: Do not write lsc to ics in msi-x mode" and/or "e1000e: Do not read ICR in Other interrupt"
On 2016/11/01 19:56, Jack Suter wrote:
> Hi there,
> I have some servers with an 82574L based NIC and recently upgraded from
> a 4.4 series kernel to 4.7. Upon doing so, servers with this chipset
> have begun frequently reporting "Link is Down" and "Link is Up"
> messages. No other related network errors are reported by the kernel or
> e1000e driver. I saw some reports about using "ethtool -s $iface msglvl
> 6" to reveal more information, but nothing extra was reported.
> Some testing showed that this was introduced between the 4.4 and 4.5
> series. I was able to further narrow it down to two commits that look
> related:
> e1000e: Do not write lsc to ics in msi-x mode
> (a61cfe4ffad7864a07e0c74969ca7ceb77ab2f1f)
> e1000e: Do not read ICR in Other interrupt
> (16ecba59bc333d6282ee057fb02339f77a880beb)

I'm just about to get on a plane but I'll be able to look at this on
Monday. Two guesses are that:
1) There is something else than LSC that triggers the "other" interrupt.
Even if that is so, it should not cause e1000e_check_for_copper_link to
report link down however.
2) The link down events are real but some lsc interrupts were not
processed properly prior to this patchset, causing the events to be

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