Re: [PATCH] mmc: add module parameter to set whether cards are assumed removable

Stefan Richter
2009-11-17T07:53:21Z

Ben Hutchings wrote:
> In general, it is not possible to tell whether a card present in an MMC
> slot after resume is the same that was there before suspend.

That's true for virtually all storage devices, not just MMC.

> So there are two possible behaviours, each of which will cause data
> loss in some cases:
>
> CONFIG_MMC_UNSAFE_RESUME=n (default): Cards are assumed to be removed
> during suspend. Any filesystem on them must be unmounted before
> suspend; otherwise, buffered writes will be lost.
>
> CONFIG_MMC_UNSAFE_RESUME=y: Cards are assumed to remain present during
> suspend. They must not be swapped during suspend; otherwise, buffered
> writes will be flushed to the wrong card.
>
> Currently the choice is made at compile time and this allows that to be
> overridden at module load time.

Can't the kernel flush the write buffer at suspend time, so that you can
remove this choice for good?
--
Stefan Richter
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