Opening a live-system dump with the crash tool

Inconsistencies in a kernel dump from a live system can cause some crash commands to fail.

Procedure

Use the crash command to find information about whether a dump is from a live system. This information is displayed in the startup messages, or when you use the sys command:
```
# crash dump.elf vmlinux vmlinux.debug
...
   KERNEL: /boot/vmlinux
 DUMPFILE: /mnt/dump.elf [LIVE DUMP]
     CPUS: 6
...
crash> sys | grep DUMPFILE
...
 DUMPFILE: dump.elf  [LIVE DUMP] 
...
```
The tag [LIVE DUMP] informs you that the dump contains inconsistencies.
Detect whether a dump is from a live system by using the help -p command:
```
# crash> help -p | grep flags2
flags2: 40 (LIVE_DUMP)
```
Use the --minimal option if the crash tool fails to start because of inconsistent data structures in the kernel dump.
With this option, crash tolerates a degree of inconsistency. However, only a subset of crash commands is then available:
```
# crash --minimal dump.elf vmlinux vmlinux.debug
...
NOTE: minimal mode commands: log, dis, rd, sym, eval, set and exit
```