KVM beta initial thoughts

Initial thoughts:

* Would be cool if "grub" in the list identified which version (1 v 2 being the big one, but even an internal build number on it would rock

  • Will KVM kernels vs Xen kernels get some API distinction, or a section on http://linode.com/kernels

  • Finnix boot showed: "System Boot - Rescue Mode – qemulinodeboot: failed to get pid"

  • Is there a way to identify KVM vs Xen in the Manager/API? Not a huge deal now, but as folks transition I suspect that'll become very important, especially for folks using API to deploy/configure

3 Replies

* Grub versions: We are on it – the text will be updated to something like Grub 2.0.0 linode 1. The post-beta hope is to gladly handle GrubV1 (menu.lst) and V2 (grub.cfg) guests via Grub2.

  • Kernel Flags: There is an ISKVM flag that we are hiding for now (akin to the current ISXEN flag).

  • Finnix boot showed: This is a debug notice that should have been redacted before the release, nothing to worry about.

  • Identify KVM vs Xen: There is no direct exposure of this status. You can indirectly identify this through the Manager Configuration Panel (/dev/sda vs /dev/xvda)

Some more thoughts:

* It looks like /sys/hypervisor/type is exposed on Xen but not KVM. No idea how hard this is to change, but would be very helpful

  • My KVM Linode is still getting/using hvc0 rather than ttyS0, and the Linode kernel cmdline is still setting console=hvc0

  • Just realized there's not a way at all (that I can find) to get a kernel ID for creating a config profile via the API, besides making one in the manager and then reading the value via the API.

  • It looks like "grub" in the list is grub-legacy, but as soon as I pick an option at the grub prompt, I lose console and everything goes technically black. I'm working on some testing to rule out a failure on my end

If anybody has a working config for either "grub" or "grub-legacy", I'd be curious to hear how you set it up / see your grub and kernel configs. So far, all my attempts end with selecting an entry on the grub prompt and then getting a black screen on console and the system hanging until I reboot.

Sample from one of my passes:

timeout 25
default 0

title latest
root (hd0)
kernel /boot/vmlinuz root=/dev/sda console=/dev/ttyS0
  • Les

Edit: Figured it out, I'm dumb. For starters, it should be console=ttyS0, not /dev/ttyS0. Also, if you disable CONFIGSERIAL8250_CONSOLE, you're gonna have a bad time. Virtio block/network options are also helpful


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