Re: Freezing Dom0

["Michael L. Hitch" <mhitch%lightning.msu.montana.edu@localhost>]

On Sun, 25 Sep 2011, Torsten Harenberg wrote:

> okay.. I managed to set up the serial console, rebooted and now run into 
> the same freezing state and are in the debugger. So I could get a full 
> bt and a dmesg, which says at the end:
>
> sd1(ciss1:0:0:0): no free tags
> panic: scsipi_get_tag
> fatal breakpoint trap in supervisor mode
> trap type 1 code 0 rip ffffffff804f5b9d cs e030 rflags 246 cr2  7f7ffdfdc000 cpl
> 6 rsp ffffa0002f691500
...
> What does this "sd1(ciss1:0:0:0): no free tags" mean? Any hint is really very 
> much appreciated.

  It means that the ciss(4) driver will accept more than 256 command, but 
the tagging done in the scsipi layer can only do 256 and a DIAGNOSTIC 
kernel will panic if more are used.  The tag passed by the scsipi layer to 
ciss(4) is ignore, as the ciss(4) handles the tagging internally.

  A current kernel shouldn't have this problem, as ciss(4) was changed 
several months ago to have a maximum of 256 command per device, but was 
not pulled up to the netbsd-5 branch.  [I have requested a pullup, so at 
some point this should be resolved for that branch.]

  To fix this now for a netbsd-5* branch kernel [until the change gets 
pulled up], you will need the change in revision 1.25 of sys/dev/ic/ciss.c.

@@ -373,7 +373,7 @@ ciss_attach(struct ciss_softc *sc)
        sc->sc_adapter.adapt_dev = (device_t) sc;
        sc->sc_adapter.adapt_openings = sc->sc_channel.chan_openings;
-       sc->sc_adapter.adapt_max_periph = sc->sc_channel.chan_openings;
+       sc->sc_adapter.adapt_max_periph = min(sc->sc_adapter.adapt_openings, 
256);
        sc->sc_adapter.adapt_request = ciss_scsi_cmd;
        sc->sc_adapter.adapt_minphys = cissminphys;
        sc->sc_adapter.adapt_ioctl = ciss_scsi_ioctl;

--
Michael L. Hitch                        mhitch%montana.edu@localhost
Computer Consultant
Information Technology Center
Montana State University        Bozeman, MT     USA