[Qemu-devel] commit 5b82b70 boot problems

[Qemu-devel] commit 5b82b70 boot problems

[Gabriel L. Somlo]

Hi Stefan,

After pulling from upstream this morning, my guest VMs were no longer
able to boot. For instance, running something like

bin/qemu-system-x86_64 -machine q35,accel=kvm -m 2048 -monitor stdio \
  -device ide-drive,bus=ide.2,drive=CD \
  -drive id=CD,if=none,snapshot=on,file=Fedora-Live-Workstation-x86_64-22-3.iso

Would just hang with a black screen, or sometimes partially display
the GRUB boot menu, and never make it any further than that.

After a bisect, I narrowed it down to 5b82b70 ("memory: RCU
ram_list.dirty_memory[] for safe RAM hotplug"); reverting that
commit got me back to where my VMs were working fine, but the
actual content of the changes isn't immediately obvious.

Apologies for the noise in case you're already aware of the problem.
Otherwise, I'd be happy to test and send you debug output.

Please advise.

Thanks much,
--Gabriel

Re: [Qemu-devel] commit 5b82b70 boot problems

[Paolo Bonzini]

On 10/02/2016 20:26, Gabriel L. Somlo wrote:
> Hi Stefan,
> 
> After pulling from upstream this morning, my guest VMs were no longer
> able to boot. For instance, running something like
> 
> bin/qemu-system-x86_64 -machine q35,accel=kvm -m 2048 -monitor stdio \
>   -device ide-drive,bus=ide.2,drive=CD \
>   -drive id=CD,if=none,snapshot=on,file=Fedora-Live-Workstation-x86_64-22-3.iso
> 
> Would just hang with a black screen, or sometimes partially display
> the GRUB boot menu, and never make it any further than that.
> 
> After a bisect, I narrowed it down to 5b82b70 ("memory: RCU
> ram_list.dirty_memory[] for safe RAM hotplug"); reverting that
> commit got me back to where my VMs were working fine, but the
> actual content of the changes isn't immediately obvious.
> 
> Apologies for the noise in case you're already aware of the problem.

No apologies needed, but indeed a fix is pending on the list (search for
"memory" in today's subjects).

Paolo

> Otherwise, I'd be happy to test and send you debug output.
> 
> Please advise.
> 
> Thanks much,
> --Gabriel
> 
>