Re: kern/57063: Kernel panic in -current in iic_attach

[Brad Spencer <brad%anduin.eldar.org@localhost>]

Paul Goyette <paul%whooppee.com@localhost> writes:

> On Tue, 18 Oct 2022, Brad Spencer wrote:
>
> <big snip>
>
>> o If you comment out the type check in dwiic_init and and try to use the
>> device I have anyway you do not appear to get a panic anywhere, but the
>> driver reports fails in other ways indicating that the device I have
>> really won't work with the driver:
>>
>> [     1.000003] dwiic0 at pci0 dev 21 function 0: I2C controller instance 0
>> [     1.000003] dwiic0: interrupting at ioapic0 pin 16
>> [     1.000003] dwiic0: failed to disable
>> [     1.000003] dwiic0: failed to disable
>> [     1.000003] iic0 at dwiic0: I2C bus
>> [     1.000003] dwiic1 at pci0 dev 21 function 1autoconfiguration error: : can't map register space
>
> Sounds to me like maybe the dwiic driver should make this ``type
> check'' during dwiic_match() and fail there.
>
>
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What Jason said..  match routines probably should not do that.

I can't work on this again right now, but looking at the driver code
suggests that return values are ignored in a number of places where they
probably should not be and this is true for all attachment types, as best
as I can tell.

I also suspect that someone else, someday, will run into this same thing
again unless I got REALLY lucky in picking a motherboard with that
particular chip variant in it (this isn't impossible, the motherboard
was designed some time ago and it may be the case that the chip I have
is older than what the driver was meant for).  There is nothing at all
that suggests that this is limited to a Xen DOM0 kernel and probably
will panic in the same way with GENERIC.




-- 
Brad Spencer - brad%anduin.eldar.org@localhost - KC8VKS - http://anduin.eldar.org