# kernel panic and safe mode



## kr651129 (Aug 27, 2012)

I tried booting into Safe [M]ode this morning, just because I never have.  I got a kernel panic.  The normal system boots fine as does single user mode.  Has anyone experienced this?  I don't have the panic output because I don't know where I would get it from.  I'd be happy to post it if I could get someone to point me in the right direction.

While I'm on the topic the FreeBSD bootloader will also freeze on me from time to time if selecting any of the options, Safe Mode, Single User, Verbose, etc.


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## izotov (Aug 28, 2012)

Once I tried and it resulted a panic on my system as well. So I forgot about it.
I do not even understand what this safe mode is good for (I know: it disables a lot of things).


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## SirDice (Aug 28, 2012)

Same here, it pretty much panics every system I tried it on. No idea what it's supposed to do though. It seems to panic(9) on the timer detection (which is different than the one the 'normal' boot uses).

I never really bothered with it. If I have issues I'll boot to single user mode anyway.


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## kpa (Aug 28, 2012)

I believe it's a relic from a time when it was possible to fall back to using BIOS calls for some of the hardware interactions instead of using the proper kernel drivers. It should be removed in my opinion. Same goes for the disable ACPI option, at least on any recent piece of hardware, they are made with the assumption that ACPI is always enabled.


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## SirDice (Aug 28, 2012)

It would be nice if "safe mode" only starts the base OS and nothing from /usr/local/etc/rc.d/, i.e. no ports. I think that would be helpful for newbies.


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## kr651129 (Aug 28, 2012)

Yeah I never use it because of single user also, I was just going into it to see what it's all about.


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## fluca1978 (Aug 30, 2012)

I've never used too, but it does not panic on my 32 bit machine (8.2-RELEASE), I don't have any upgraded release to test right now. However if I get ir right from the meny settings the safe mode disables _acpi_, _apic_ and the dma for ATA drives. The DMA and apic are extra parts with regards to booting with ACPI disable from the menu.


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