Re: revisiting tunables under Safe Mode menu option

On Feb 28, 2012, at 6:44 AM, John Baldwin wrote:

> On Monday, February 27, 2012 2:03:21 pm Scott Long wrote:
>>=20
>> On Feb 27, 2012, at 3:45 AM, Andriy Gapon wrote:
>>=20
>>> on 30/01/2012 18:59 Andriy Gapon said the following:
>>>>=20
>>>> First, I think that this proposal/discussion could have been more =
useful before
>>>> the 9.0.  Maybe the RE would be interested in adding another item =
to their
>>>> pre-release checklist: ask developers about what could be dropped =
and what should
>>>> be added to the Safe Mode settings in a new (.0) release.  Probably =
the developers
>>>> should keep the Safe Mode in mind too when adding new features or =
making other
>>>> drastic changes, but the reminder should be welcome.
>>> [snip]
>>>> o Since we have a separate ACPI option and because ACPI now is =
almost a mandatory
>>>> thing (and not a significant source of boot troubles), maybe we =
could remove the
>>>> code that automatically disables ACPI in Safe Mode?
>>>>=20
>>>> o hint.apic.0.disabled - APIC code doesn't seem to be a significant =
source of boot
>>>> troubles, like ACPI it has become almost a mandatory thing.  So =
maybe we should
>>>> remove this setting?
>>=20
>> Turning off the APIC turns off SMP in a very efficient, clean manner. =
 I added this not to isolate the APIC code, but to turn off SMP.  That's =
why=20
> it's there, and I'd like the ability to turn off SMP to stay there in =
some form.  If there's a better way to disable SMP that doesn't get into=20=

> problems with interrupt delivery, then please propose it.  As for it =
being mandatory, it's really only mandatory for MSI these days, though =
it used=20
> to be required for more complex PCIX topologies.
>=20
> You want APIC for other things as well (hwpmc(4) requires it, as do =
CMCI
> interrupts, and we really do like to make use of the local APIC =
timer).
>=20

Well, 'Safe Mode' isn't meant to be a normal, continuous operating mode, =
it's meant to be a debug mode that helps boot otherwise unbeatable =
systems.

Scott

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