One of the many new things merged into 2.6.5-rc1 is the "netpoll"
infrastructure. Netpoll exists to support low-level kernel functions which
may need to be able to send and receive packets over the network without
involving the entire networking subsystem and without enabling interrupts.
Examples include kgdbeth
(which allows kernel debugging over the
net), and netconsole, which enables remote, network-based consoles. The
patches have been around (and in the -mm tree) for some time, but have only
now found their way into the mainline. Netconsole was merged as well, but
kgdbeth users will still have to apply patches for now.
Supporting netconsole in network drivers turns out to be relatively easy -
for most adaptors. There is a new net_device method called
poll_controller(); its job is to catch up with whatever the device
has been doing. For many devices, this method looks like this:
static void poll_my_card(struct net_device *dev);
Netpoll, in other words, is simulating device interrupts from within the
kernel. Some device interrupt handlers may need tweaks to ensure that they
do all of the necessary work without a real hardware interrupt, but most
seem to work as they are.
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