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Date: Sun, 24 Sep 1995 15:57:25 +1000
From: Bruce Evans <bde@zeta.org.au>
Message-Id: <199509240557.PAA18367@godzilla.zeta.org.au>
To: freebsd-hackers@freebsd.org, hm@altona.hamburg.com
Subject: Re: LKM: how to fiddle in interrupt routine ptrs ?
Sender: owner-hackers@freebsd.org
Precedence: bulk

>Is there a generic or recommended way or example of installing a device's
>interrupt routine at mod-loading a device driver LKM time ?

See pcibus.c:pcibus_ihandler_attach/detach.

There are some minor problems with these routines:

- the `func' arg should already have the correct type (inthand2_t).
- `deviced??' should be spelled `device_id??'
- it isn't possible to give a correect device_id.  0 is for clkintr.
  The device_id is only used for counting interrupts.  To fix this
  you would have to expand the string table in vector.s and edit it.
- 1ul should be 1u.
- update_intr_masks() and INTREN() and INTRDIS() may need to be called
  at a high ipl or with interrupts disabled.  The whole routines may
  need to be called at a high ipl or with interrupts disablied.
- INTRDIS() in pci_ihandler_detach() isn't right if several devices
  are sharing the interrupt.
- INTRDIS() in pci_ihandler_detach() isn't right if the unregister_intr()
  fails.

>Does one have to copy the old isa_devtab_xxx[], expand it with an entry
>and exchange it with a new one ?

That might work.  You would have to edit the interrupt name string table
too.  It would be better to supply a dummy driver and replace that,

>What is the way to tell the driver at mod-load time it's IRQ and i/o addr ?

There is no way.  You could use the values from the dummy driver.  These
values can be handled using standard methods (config, userconfig, dset).

Bruce