Re: Panic with "Unrecoverable machine check exception"

> Thanks for the quick reply.  You're probably correct about 
> a hardware issue.  This system is getting long in the tooth.
> Panic occurs if I run a few very intensive floating point
> computations.  Console logs do not show anything unusual.
> I need to go investigate how to up BMC.

Check for CPU overheating, as systems age the thermal compound
between the CPU and heatsink often becomes dryed and ineffective.
 
> -- 
> steve
> 
> 
> On Fri, Jun 27, 2025 at 04:52:53PM -0400, Alexander Motin wrote:
> > Hi.
> > 
> > It is likely a hardware failure, unless a false positive. Check last
> > console logs or better BMC logs for detail.
> > 
> > On Fri, Jun 27, 2025, 16:26 Steve Kargl <sgk@troutmask.apl.washington.edu>
> > wrote:
> > 
> > > Never seen this type of panic.  I can upload
> > > core.txt.4 and info.4 to freefall if someone
> > > wants more details.
> > >
> > >
> > > __curthread () at /usr/src/sys/amd64/include/pcpu_aux.h:57
> > > 57              __asm("movq %%gs:%c1,%0" : "=r" (td)
> > > (kgdb) #0  __curthread () at /usr/src/sys/amd64/include/pcpu_aux.h:57
> > >         td = <optimized out>
> > > #1  doadump (textdump=textdump@entry=1)
> > >     at /usr/src/sys/kern/kern_shutdown.c:399
> > >         error = 0
> > >         coredump = <optimized out>
> > > #2  0xffffffff80676e30 in kern_reboot (howto=260)
> > >     at /usr/src/sys/kern/kern_shutdown.c:519
> > >         once = 0
> > >         __pc = 0x0
> > > #3  0xffffffff80677367 in vpanic (
> > >     fmt=0xffffffff80abdb94 "Unrecoverable machine check exception",
> > >     ap=ap@entry=0xfffffe001c024ed0) at
> > > /usr/src/sys/kern/kern_shutdown.c:974
> > >         buf = "Unrecoverable machine check exception", '\000' <repeats 218
> > > times>
> > >         __pc = 0x0
> > >         __pc = 0x0
> > >         __pc = 0x0
> > >         other_cpus = {__bits = {251, 0 <repeats 15 times>}}
> > >         td = 0xfffff80004601000
> > >         bootopt = <unavailable>
> > >         newpanic = <optimized out>
> > > #4  0xffffffff80677193 in panic (fmt=<unavailable>)
> > >     at /usr/src/sys/kern/kern_shutdown.c:887
> > >         ap = {{gp_offset = 8, fp_offset = 48,
> > >             overflow_arg_area = 0xfffffe001c024f00,
> > >             reg_save_area = 0xfffffe001c024ea0}}
> > > #5  0xffffffff809d391b in mca_intr () at /usr/src/sys/x86/x86/mca.c:1540
> > >         recoverable = false
> > >         mcg_status = <optimized out>
> > >         count = <optimized out>
> > >         lmcs = <optimized out>
> > > #6  <signal handler called>
> > > No locals.
> > > #7  mi_switch (flags=flags@entry=262) at
> > > /usr/src/sys/kern/kern_synch.c:537
> > >         __pc = 0x0
> > >         __pc = 0x0
> > >         __pc = 0x0
> > >         __pc = 0x0
> > >         __pc = 0x0
> > >         td = 0xfffff80004601000
> > >         new_switchtime = <optimized out>
> > >         runtime = <optimized out>
> > > #8  0xffffffff806aaca4 in sched_idletd (dummy=dummy@entry=0x0)
> > >     at /usr/src/sys/kern/sched_4bsd.c:1688
> > >         __pc = 0x0
> > >         stat = <optimized out>
> > > #9  0xffffffff806324b2 in fork_exit (
> > >     callout=0xffffffff806aac50 <sched_idletd>, arg=0x0,
> > >     frame=0xfffffe00d5407f40) at /usr/src/sys/kern/kern_fork.c:1153
> > >         __pc = 0x0
> > >         __pc = 0x0
> > >         td = 0xfffff80004601000
> > >         p = 0xfffffe00c3002040
> > >         dtd = <optimized out>
> > > #10 <signal handler called>
> > >
> > >
> > >
> > >
> > >
> > >
> > > --
> > > Steve
> > >
> > > --
> > Alexander Motin
> 
> -- 
> Steve
> 
> 

-- 
Rod Grimes                                                 rgrimes@freebsd.org