[kvm-devel] [ kvm-Bugs-1952988 ] in-kernel PIT blocks DragonFlyBSD from booting

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Bugs item #1952988, was opened at 2008-04-27 18:25
Message generated for change (Comment added) made by mtosatti
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Category: kernel
Group: None
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: Carlo Marcelo Arenas Belon (carenas)
Assigned to: Nobody/Anonymous (nobody)
Summary: in-kernel PIT blocks DragonFlyBSD from booting

Initial Comment:
starting with kvm 64, DragonFlyBSD guests won't be able to boot unless -no-kvm-pit or -no-kvm-irqchip is used (-no-kvm works as well) :

    cpu model: Intel(R) Core(TM)2 CPU
  kvm version: kvm 66 (kvm>=64 fails, kvm<=63 works)
  host kernel: 2.6.24-gentoo-r4 (SMP)
    host arch: x86_64

to replicate, download dragonfly ISO (it is a livecd) and boot from it :

  kvm -curses -cdrom dfly-1.12.2_REL.iso -boot d

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Comment By: Marcelo Tosatti (mtosatti)
Date: 2008-04-28 17:30

Message:
Logged In: YES 
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Originator: NO

DragonFlyBSD uses mode 4 of the PIT which the in-kernel emulation
simply ignores.

Mode 4 seems to be similar to one-shot mode, other than the fact
that mode 4 starts counting after the next CLK pulse once programmed,
and mode1 starts counting immediately, so this _should_ be OK:

http://people.redhat.com/~mtosatti/kvm-i8254-mode4.patch

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You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=893831&aid=1952988&group_id=180599