Hello everyone!
I've found strange behavior of reading /dev/mem:
for i in 0 1 2; do
echo $i
dd if=/dev/mem of=/dev/null skip=$((6+$i)) bs=$((0x20000000)) count=1
done
On some systems with Supermicro X8DTU I've got several messages during
first 512Mb starting from 0xc000_0000:
"BUG: soft lockup - CPU#xx stuck for 61s!"
On other systems with the sameboard I've stuck without any errors at
last 10Mb before 0x1_0000_0000. Local APIC access?
On E5440 (Dell PowerEdge 1950) I've just got several:
APIC error on CPU3: 00(80)
APIC error on CPU3: 80(80)
...
APIC error on CPU3: 80(80)
That looks like wrong register access.