svn commit: r192050 - in head/sys: amd64/amd64 amd64/include conf i386/i386 i386/include

Alan Cox alc at
Sat May 16 18:39:35 UTC 2009

John Baldwin wrote:
> Author: jhb
> Date: Wed May 13 17:53:04 2009
> New Revision: 192050
> URL:
> Log:
>   Implement simple machine check support for amd64 and i386.
>   - For CPUs that only support MCE (the machine check exception) but not MCA
>     (i.e. Pentium), all this does is print out the value of the machine check
>     registers and then panic when a machine check exception occurs.
>   - For CPUs that support MCA (the machine check architecture), the support is
>     a bit more involved.
>     - First, there is limited support for decoding the CPU-independent MCA
>       error codes in the kernel, and the kernel uses this to output a short
>       description of any machine check events that occur.
>     - When a machine check exception occurs, all of the MCx banks on the
>       current CPU are scanned and any events are reported to the console
>       before panic'ing.
>     - To catch events for correctable errors, a periodic timer kicks off a
>       task which scans the MCx banks on all CPUs.  The frequency of these
>       checks is controlled via the "hw.mca.interval" sysctl.
>     - Userland can request an immediate scan of the MCx banks by writing
>       a non-zero value to "hw.mca.force_scan".
>     - If any correctable events are encountered, the appropriate details
>       are stored in a 'struct mca_record' (defined in <machine/mca.h>).
>       The "hw.mca.count" is a count of such records and each record may
>       be queried via the "hw.mca.records" tree by specifying the record
>       index (0 .. count - 1) as the next name in the MIB similar to using
>       PIDs with the kern.proc.* sysctls.  The idea is to export machine
>       check events to userland for more detailed processing.
>     - The periodic timer and hw.mca sysctls are only present if the CPU
>       supports MCA.
>   Discussed with:	emaste (briefly)
>   MFC after:	1 month
> Added:
>   head/sys/amd64/amd64/mca.c   (contents, props changed)
>   head/sys/amd64/include/mca.h   (contents, props changed)
>   head/sys/i386/i386/mca.c   (contents, props changed)
>   head/sys/i386/include/mca.h   (contents, props changed)
> Modified:
>   head/sys/amd64/amd64/machdep.c
>   head/sys/amd64/amd64/mp_machdep.c
>   head/sys/amd64/amd64/trap.c
>   head/sys/amd64/include/specialreg.h
>   head/sys/conf/files.amd64
>   head/sys/conf/files.i386
>   head/sys/i386/i386/machdep.c
>   head/sys/i386/i386/mp_machdep.c
>   head/sys/i386/i386/trap.c
>   head/sys/i386/include/specialreg.h

After this change my Phenom II locks up hard within minutes of booting.  
There are no messages, and I am unable to break into the debugger from a 
serial console.

The same exact kernel is running fine on a Core 2 Quad.


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