Debugging Kernel Panics - but /var/crash empty

[sandyd]

I am currently running Ubuntu 12.10.
Both in 12.04, and 12.10, I have been noticing random Kernel Panics that seem to happen only when I am not using the laptop.

I went to follow the guide for getting the crash dump, but after a simulated crash (using sysreq c), /var/crash is empty. It is also empty after one of those random Kernel Panics.

I have confirmed that crashdump has been added to my grub, and loaded (dmesg)

cat /proc/cmdline

BOOT_IMAGE=/vmlinuz-3.5.0-25-generic root=UUID=f84dd846-ad9e-4b58-93dc-8d48020f9089 ro rootflags=subvol=@ crashkernel=384M-2G:64M,2G-:128M quiet splash acpi_osi= vt.handoff=7

dmesg -i | grep crash

[    0.000000] Command line: BOOT_IMAGE=/vmlinuz-3.5.0-25-generic root=UUID=f84dd846-ad9e-4b58-93dc-8d48020f9089 ro rootflags=subvol=@ crashkernel=384M-2G:64M,2G-:128M quiet splash acpi_osi= vt.handoff=7
[    0.000000] Reserving 128MB of memory at 720MB for crashkernel (System RAM: 5995MB)
[    0.000000] Kernel command line: BOOT_IMAGE=/vmlinuz-3.5.0-25-generic root=UUID=f84dd846-ad9e-4b58-93dc-8d48020f9089 ro rootflags=subvol=@ crashkernel=384M-2G:64M,2G-:128M quiet splash acpi_osi= vt.handoff=7

EDIT: it now appears that kexec/kdump is not loading after the crash - system is not restarting


Any ideas?