FP register corruption in Exynos 4210 (Cortex-A9)

Russell King - ARM Linux linux at arm.linux.org.uk
Mon Dec 22 15:50:24 PST 2014

On Mon, Dec 22, 2014 at 08:42:02PM -0300, Lanchon wrote:
> On 12/22/2014 08:29 PM, Russell King - ARM Linux wrote:
> >On Mon, Dec 22, 2014 at 07:46:27PM -0300, Lanchon wrote:
> >>however under some circumstances the kernel did the wrong thing: it didn't
> >>reload the registers even though it was needed, probably because the
> >>hardware had been powered down and had lost state without the tracking code
> >>getting word of it. just disabling the optimization made the kernel solid.
> >Right, so mainline kernel's don't exhibit the behaviour...
> >
> >>a couple of days later the root cause seems to have been identified and
> >>fixed. i describe the whole thing here:
> >>http://forum.xda-developers.com/galaxy-s2/development-derivatives/kernel-fpbug-stable-4-x-kernel-galaxy-t2978088
> >... because it's a local issue with cpuidle not calling the appropriate
> >CPU PM functions, and that means there's no patches that we need to deal
> >with for mainline kernels, right?
> >
> that's what i think, yes. i only got back here on the list to thank you and
> let you know what was wrong since you helped me a couple of months ago.

Please let us know if anything changes, thanks.

And have a Merry Christmas.

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