[Cryptech Tech] Alpha board flash

[Fredrik Thulin]

On Tuesday, January 12, 2016 11:41:32 AM Rob Austein wrote:
> If I understand correctly, the current schematics have both hard-wired
> flash for the ARM CPU and also space for an SD card, with the ARM set
> up to boot (only) from the hard-wired flash.
> 
> a) Is this correct?
> 
> b) If so, why do we have the SD card, and is its intended purpose
>    serious enough to merit including yet another driver?
> 
>    Keep in mind that removing the SD card presumably involves breaking
>    the tamper envelope, thus wiping the key store.
> 
> c) Why are we using hard-wired flash at all, instead of, eg, just
>    booting from an SD card?  Fear of SD card complexity (if so, see
>    (b)...)?
> 
> d) If I understand correctly (questionable), SD cards take care of
>    wear leveling.  I'm guessing that the hardwired flash envisioned
>    for the Alpha board does not, ie, that our driver for the
>    hard-wired flash may need to deal with wear-leveling itself.
> 
>    I don't really know how many write cycles we expect the hard-wired
>    flash to have, so I'm not sure how serious an issue this is.
> 
> Apologies if some of this is a bit vague, software guy trying to
> understand reasoning behind hardware choices.

Bump. I agree with Rob - the SD card does not appear that useful since 
we left the ARM A9 track. I propose we remove it from the Alpha, unless 
someone has a good use case in mind (Jakob explicitly CC:d).

/Fredrik
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