revisiting tunables under Safe Mode menu option

Nathan Whitehorn nwhitehorn at
Mon Jan 30 17:34:16 UTC 2012

On Jan 30, 2012, at 11:30 AM, Ian Lepore wrote:

> 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.

I second the point about ATA DMA, but it is worth pointing out that  
those sysctls don't do anything with ATA_CAM (see 

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