Running as /sbin/init throws segfaults

[Florian Margaine]

To reproduce, fire up a small VM, connect to ssh into it, run `echo 'root:root' | chpasswd` for convenience, and then:

```
# cd /sbin/
/sbin/# mv init init.bak
/sbin/# cat > init <<EOF
#!/usr/bin/sbcl --noinform

(sb-impl::toplevel-repl nil)
EOF
/sbin/# chmod +x init
/sbin/# reboot
```

After the reboot, you should be thrown in the REPL. A dozen of segfaults appear before displaying the REPL prompt.

[Florian Margaine (florian-d)]

Sorry, the "connect to ssh into it" is wrong, you should connect into it via some serial console, e.g. virtualbox view. This bare init system won't have any network, so you won't be able to ssh into it once rebooted.

[Douglas Katzman (dougk)]

Really, the only repro instruction we have are to "fire up a small VM" ?

For starters - what's "small" mean? What CPU, what OS (I'll assume Linux), what distro, what kernel, what modules ...
And what SBCL revision, what build features, what heap size?
What's in SBCL's sysinit file? Were the sources pristine?
And since this is a VM - what hypervisor/virtualizer/simulator/emulator?
What physical CPU is that running on? What options were given to the VM?

Were all that information supplied, it might be possible for a developer to confirm the problem.
Even then it's likely to just say this is infeasible.