revisiting tunables under Safe Mode menu option
scottl at samsco.org
Tue Feb 28 15:22:58 UTC 2012
On Feb 28, 2012, at 6:44 AM, John Baldwin wrote:
> On Monday, February 27, 2012 2:03:21 pm Scott Long wrote:
>> On Feb 27, 2012, at 3:45 AM, Andriy Gapon wrote:
>>> on 30/01/2012 18:59 Andriy Gapon said the following:
>>>> 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.
>>>> 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?
>>>> 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?
>> 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
> 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
> 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
> to be required for more complex PCIX topologies.
> 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).
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.
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