PCI SIO devices hog interrupts, cause lock order problems

Drew Derbyshire ahd at kew.com
Mon Aug 30 12:23:17 PDT 2004

> From imp at bsdimp.com  Mon Aug 30 14:50:50 2004
> : Basically, any PCI SIO device hogs its interrupt if the PUC device is not
> : also in the kernel, and this causes real problems for any environment like
> : mine where pulling the modem is not trivial.  Does the distributed GENERIC
> : kernel have room for the PUC device?  Are there side effects that PUC should
> : be excluded from GENERIC?
> puc should be in GENERIC, imho.

Who makes the call (or the commit)?  The cost is ~ 55K on disk
(which seems excessive) with current build, I assume that's bloated
by the current kernel options.

> : As a bonus, there appears to be a bug with kernel locking exposed by the
> : problem.  With the stock generic kernel, the XL device reports it couldn't
> : map the interrupt, and then a lock order reversal is reported.  (See the
> : attached log for the gory details).
> This is a known problem.

Well, it at least it didn't panic on me, which previous experiments
(months ago) were prone to do.  


p.s. Sorry about the original mail being ugly MS HTML.  I needed the MIME, not the HTML.

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