revisiting tunables under Safe Mode menu option

Ian Lepore freebsd at
Mon Jan 30 17:30:34 UTC 2012

On Mon, 2012-01-30 at 18:59 +0200, Andriy Gapon wrote:
> o hw.ata.ata_dma, hw.ata.atapi_dma - I am not sure if there have been any
> significant problems with ATA DMA recently.  Maybe these could be removed?

I still have to work with hardware that requires ata_dma disabled.  It
seems to be required for most systems I've worked with that have a
compact flash socket on the mainboard (sometimes you can just limit the
mode to udma33 or less, sometimes you have to turn it off completely.)

Adding kern.eventtimer.periodic=1 seems like a good idea.

As a general philosophical thing, I don't have a problem with the idea
"safe mode turns off everything that has ever historically been
problematic," because I don't think anyone expects a system to run well
in safe mode.  I see it more as a tool to start narrowing down the area
of trouble, like step 1 of a binary search for the problem.  As such,
the most important aspect is a comprehensive list of what changes for
safe mode, so that you can procede by selectively en/disabling the
various things it does.

-- Ian

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