Safe-mode on amd64 broken
naylor.b.david at gmail.com
Wed Sep 29 16:20:12 UTC 2010
On Wednesday 29 September 2010 16:19:08 Andriy Gapon wrote:
> on 29/09/2010 16:47 David Naylor said the following:
> > On Wednesday 29 September 2010 15:14:08 John Baldwin wrote:
> >> On Wednesday, September 29, 2010 7:37:15 am Andriy Gapon wrote:
> >>> on 29/09/2010 13:40 Alexander Motin said the following:
> >>>> Hi.
> >>>> David Naylor wrote:
> >>>>> Trying to boot a recent (sep 23) amd64 kernel in safe-mode fails with
> >>>>> ``panic: No usable event timer found!''. This occurs on two (all my)
> >>>>> machines. This has been a persistent problem since the introduction
> >>>>> of the event timer code.
> >>>> I've reproduced the problem.
> >>>> The reason is that all (or at least most) of devices (both PCI and
> >>>> ISA), including only available in that mode i8254 and RTC timers,
> >>>> failed to allocate their interrupts. While reported message is indeed
> >>>> related to event timer code, problem IMHO doesn't. While without this
> >>>> panic system could boot without any alive timer, I have doubts that it
> >>>> would be functional without timers, USB, network and disk controllers.
> >>>> Problems seems to be the same if I am trying to boot without ACPI.
> >> Probably the kernel doesn't have 'device atpic' so disabling APIC
> >> probably breaks all interrupts. A newer system might only describe
> >> APICs via the ACPI MADT table and not provide an MP Table. In that
> >> case disabling ACPI would effectively disable APIC leading to the same
> >> result.
> > Is APIC and ACPI disabled in safe-mode on amd64?
> Did you notice the code snippet below?
Yes, and it managed to confuse me.
> Specifically hint.acpi.0.disabled and hint.apic.0.disabled.
> Don't let "arch-i386" confuse you, it means "x86" in that context.
> > This is using GENERIC, perhaps atpic should be added to the config file,
> > or made mandatory for amd64 systems?
> I don't think so. Especially given that hardware might not support !APIC
> case at all, even if you have atpic in your kernel.
Perhaps safe-mode is no longer a viable option and should be removed from the
boot menu, or renamed to "unsafe-mode"?
> Alternatively, perhaps just don't use this "Safe Mode"?
> What do you try to actually achieve?
I was trying to boot a system and it was panicking due to stray interrupts.
It turned out to be caused by HPET. I found `hint.hpet.0.clock=0' which fixed
This means HPET does not work on any of my machines. The other one's symptoms
are hda losing interrupts after a period of up-time.
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