freebsd stable - Jul 2015 - r284665 causes MSI problems -> ahcich2: Timeout in slot 11 port 0

Hello,

r284665 causes ahci(4) to fail with timeouts when using MSI (the default).

'hint.ahci.0.msi=0' is one way to make ahci(4) working with r284665, but
obviously not the desired solution, it just disables usage of an MSI.

I can't find suspicious code in r282213 which could cause this strange
regression, but I verified carefully that problem arises with r284665.
Actually, r282901
(https://svnweb.freebsd.org/base?view=revision&sortby=date&revision=282901)
is the real trigger, verified by putting
nooptions         RACCT
nooptions         RACCT_DEFAULT_TO_DISABLED
nooptions         RCTL
into my kernel config -> problem vanishes!

Setting "kern.racct.enable=1" doesn't make any difference, as soon
as
'kern.features.racct' exists, there's the ahci(4)/ahcich2 timeout
and
machine doesn't finish booting.

Unfortunately, I don't have any idea how to track this down to the
actual culprit, but I hope the RACCT hackers do have ;-)

Shall I open a bugzilla ticket?

Thanks,

-Harry

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On 0711T1956, Harald Schmalzbauer wrote:
>  Hello,
> 
> r284665 causes ahci(4) to fail with timeouts when using MSI (the default).
What's the hardware?
> 'hint.ahci.0.msi=0' is one way to make ahci(4) working with
r284665, but
> obviously not the desired solution, it just disables usage of an MSI.
> 
> I can't find suspicious code in r282213 which could cause this strange
> regression, but I verified carefully that problem arises with r284665.
> Actually, r282901
>
(https://svnweb.freebsd.org/base?view=revision&sortby=date&revision=282901)
> is the real trigger, verified by putting
> nooptions         RACCT
> nooptions         RACCT_DEFAULT_TO_DISABLED
> nooptions         RCTL
> into my kernel config -> problem vanishes!
> 
> Setting "kern.racct.enable=1" doesn't make any difference, as
soon as
> 'kern.features.racct' exists, there's the ahci(4)/ahcich2
timeout and
> machine doesn't finish booting.
> 
> Unfortunately, I don't have any idea how to track this down to the
> actual culprit, but I hope the RACCT hackers do have ;-)
> 
> Shall I open a bugzilla ticket?
That's... curious.  I don't see how those two things could be related.
What's the FreeBSD version?  How reproducible it is?  Have you tried
compiling with and without those three lines a couple of times?