Enabling MCA causes system hangs
doconnor at gsoft.com.au
Fri Sep 10 07:46:47 UTC 2010
On 10/09/2010, at 16:58, Andriy Gapon wrote:
>> The motherboard is a Gigabyte GA-MA785GM-US2H with an Athlon II X2 240 CPU &
>> 4Gb of RAM.
> Do you also have superpages enabled (vm.pmap.pg_ps_enabled)?
> If so, please try to turn them off and report back if that helps.
Yes, they are - I will try without.
> If not, then it's a tougher situation.
> What you see looks like a consequence of HyperTransport sync flood, which is a
> way to handle certain errors detected by CPU. Essentially it means that all
> HyperTransport communications are frozen. A system just hangs.
> My impression is that consumer-type systems are often configured to produce sync
> flood to stop error propagation in situations where more 'serious' systems would
> report machine check exception (MCE), probably an uncorrectable one.
The system does seem to operate normally without MCA and I haven't noticed any data corruption issues. FWIW I am using ZFS on this box and haven't seen any complaints about corrupt files.
> NOTE: the following may hurt your system and your data!
> Please stop reading if you are unsure if you can handle that!
Woooh, sounds fun :)
> You may try to investigate the sync flood situation further by checking the
> following bit in CPU configuration:
> F3x180 Extended NB MCA Configuration Register
> 21 SyncFloodOnCpuLeakErr: sync flood on CPU leak error enable.
> You can examine current value with a command like the following:
> $ pciconf -r pci0:0:24:3 0x180
> Where pci0:0:24:3 is PCI handle that corresponds to the device reported as
> follows by pciconf -lv:
> '(Family 10h) Athlon64/Opteron/Sempron Miscellaneous Control'
> If the bit is set, you can try to flip it off (using pciconf -w) and see how
> your system behaves when the MCA condition strikes.
It does look like it is set:
hostb4 at pci0:0:24:3: class=0x060000 card=0x00000000 chip=0x12031022 rev=0x00 hdr=0x00
vendor = 'Advanced Micro Devices (AMD)'
device = '(Family 10h) Athlon64/Opteron/Sempron Miscellaneous Control'
class = bridge
subclass = HOST-PCI
[midget 17:09] /usr/src/sys >sudo pciconf -r pci0:0:24:3 0x180
0 0 f 0 0 3 e 2
0000 0000 1111 0000 0000 0011 1110 0010
| | | | | | | | |
31 27 23 19 15 11 7 3 0
> Be careful and cautious.
Thanks, I'll let you know how I go!
Daniel O'Connor software and network engineer
for Genesis Software - http://www.gsoft.com.au
"The nice thing about standards is that there
are so many of them to choose from."
-- Andrew Tanenbaum
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