device_detach() on a device used by ixgbe driver (FreeBSD
7-STABLE through to 9-CURRENT)
John Baldwin
jhb at freebsd.org
Mon May 23 14:32:22 UTC 2011
On Monday, May 23, 2011 10:13:41 am Philip Soeberg wrote:
> Hi fellow FreeBSD hackers,
>
> I've just completed designing a new driver for the Intels IXGBE suite of
> network adapters, but is building my driver as a kernel module to be
> loaded after system boot.
>
> The current sys/dev/ixgbe/ixgbe.c driver which attach to Intels adapters
> return a zero in it's probe() function (which equals to
> BUS_PROBE_SPECIFIC).. This has the distinct disadvantage that I cannot,
> through my module, call a device_detach() on the devices I support, and
> afterward expect being probed for them. A BUS_PROBE_SPECIFIC, according
> to wording in sys/sys/bus.h, inform the OS that "Only I can use this
> device".
>
> I assume this (transcanding from FreeBSD 7.0-STABLE through to FreeBSD
> 9-CURRENT) is in error? I would expect sys/dev/ixgbe/ixgbe.c's probe()
> function to return BUS_PROBE_DEFAULT, which is the "Base OS default
> driver"..
Yes, that is true.
> If this is true, then we should probably also update
> sys/kern/device_if.m's description of the probe() method as to reflect
> the BUS_PROBE_* return values in a clearer way than is currently described.
> Do you want me to provide a patch? (it's really a one liner for ixgbe.c
> and a couple of alterations to the device_if.m, if need be)
device_if.m was probably just never updated from when BUS_PROBE_* were added.
Updating it would be a good thing.
> I would also expect the ixgbe.c driver to do a quick resource_disabled()
> in it's attach() function, so that we can disable specific adapters
> through kenv hint.ix.0.disabled=1..
That is not universally supported (i.e. it's not a part of new-bus
specifically). For buses that support hinted devices, they do all generally
support being able to disable a hinted device, but disabling bus-enumerated
devices is not generally supported.
> Given that I can't use device_detach() on a device hogged by the IXGBE
> driver, can any one of you help me with a way around this problem? I
> can't use the hints, and I can't detach() the device.. how can I get my
> kernel module to attach the device?
I think ixgbe has to be fixed to use BUS_PROBE_DEFAULT. Very few drivers
should use '0' for their probe return value.
--
John Baldwin
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