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    SubjectRe: [PATCHv3 1/3] NETPOLL: Extend rx_hook support.
    Hi,

    ----- Original Message -----
    > From: "Jason Wessel" <jason.wessel@windriver.com>
    > To: "Andrei Warkentin" <awarkentin@vmware.com>
    > Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, "Andrei Warkentin" <andreiw@vmware.com>,
    > kgdb-bugreport@lists.sourceforge.net, "Matt Mackall" <mpm@selenic.com>, "Andrei Warkentin"
    > <andrey.warkentin@gmail.com>
    > Sent: Tuesday, February 28, 2012 11:06:44 AM
    > Subject: Re: [PATCHv3 1/3] NETPOLL: Extend rx_hook support.
    >

    >
    > All that netpoll_poll() did was to call netpoll_poll_dev(). I have
    > not yet looked at the differences between kgdboe and the netkdb code
    > you proposed but I would have suspected it also falls victim to the
    > ethernet preemption problem which prevented kgdboe from ever being
    > considered for a mainline merge. Certainly there are ways to fix
    > this
    > problem but most involved changes to scheduling, core net code, or
    > substantial driver specific changes.
    >

    I see, I read up on the issues w.r.t. preemption. Could this be worked
    around by modifiying affected drivers to bypass locking if they are
    used in KDB context? Make some accessor netdev-specific lock/unlocks
    that won't do anything if running in KDB context.

    >
    > >
    > > This is slight OT, but...are WiFi drivers sufficiently similar that
    > > netpoll "just works?"
    >
    > Yes and no. Yes, you could use the NET_POLL api to transmit packets
    > if the driver implemented polling hooks, but no in the sense that
    > most
    > of the time you need a user space driver to manage the keys which are
    > time sensitive for things like WPA (usually the job of wpa
    > supplicant). This is going to prevent you from having WiFi work at
    > all while the kernel is in the critical exception state.
    >

    Ah right. I was thinking just open networking. I should give that a try...

    A


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