question on Ethernet Devicedriver - Linux

This is a discussion on question on Ethernet Devicedriver - Linux ; Hi all, 1) Iam working on Philips LPC 2292 controller board, Ethernet controller is Rtl8019 and Iam testing Rtl8019 driver on linux 2.6 Kernel.I have few Doubts. 2) If at all if a single packet comes and sits in Rx ...

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Thread: question on Ethernet Devicedriver

  1. question on Ethernet Devicedriver

    Hi all,
    1) Iam working on Philips LPC 2292 controller board, Ethernet
    controller is Rtl8019 and Iam testing Rtl8019 driver on linux 2.6
    Kernel.I have few Doubts.

    2) If at all if a single packet comes and sits in Rx Buffer. Whether
    my ethernet controller immediately raises an Interrupt or it wait for
    Few seconds or milliseconds for another packets to sit in Rx Buffer
    before it raises an Interrupt.

    3) If at all If ISR is Executing and if Before copying a packet from
    Rx Buffer to local Buffer, if few packet comes to Eth controller,
    will respective packets sits in Rx Buffer or packets are Denied by
    Ethernet controller.

    Thanks in advance,
    Bab

  2. Re: question on Ethernet Devicedriver

    "srblinux@gmail.com" writes:
    > 2) If at all if a single packet comes and sits in Rx Buffer. Whether
    > my ethernet controller immediately raises an Interrupt or it wait for
    > Few seconds or milliseconds for another packets to sit in Rx Buffer
    > before it raises an Interrupt.


    Immediatly. A sensibly written NIC interrupt handler (ie not the way
    the usual copy-it-from-elsewhere-and-modify-as-needed Linux NIC
    interrupt handler usually looks like) would just (assuming
    level-triggered IRQs) mask the IRQ source and schedule a tasklet to
    actually act on the RX interrupt (or use NAPI to de facto accomplish
    the same), and this tasklet would then process all received frames
    (BTW, consider using skbs as 'RX buffers') before acknowledging and
    unmasking the IRQ again (taking proper care to avoid lost wakeups).

    Consequently, if another frame arrives 'soon', it will be processed by
    the same evocation of the 'interrupt handler bottom half' and if not,
    the first frame will just have been uselessly delayed for some time.

    > 3) If at all If ISR is Executing and if Before copying a packet from
    > Rx Buffer to local Buffer, if few packet comes to Eth controller,
    > will respective packets sits in Rx Buffer or packets are Denied by
    > Ethernet controller.


    ?

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