Re: [PATCH 1/1] arm: imx: fsl_otp: make fuses (OTP memory) read-only

[Alexander Holler <holler@ahsoftware.de>]

Am 07.11.2014 um 12:34 schrieb Otavio Salvador:
> On Fri, Nov 7, 2014 at 7:43 AM, Alexander Holler <holler@ahsoftware.de> wrote:
>> Nothing in userspace should be able to kill the HW.
>> Not even just as root and for sure not that easy.
>>
>> For obvious reason, I haven't tested this patch thoroughly.
>>
>> Reported-by: Jon Nettleton <jon.nettleton@gmail.com>
>> Signed-off-by: Alexander Holler <holler@ahsoftware.de>
>
> I have a mix of feelings about the patch.
>
> Long story, short:
>
>  - We ought to have a FSL_OTP_WRITE_SUPPORT config option
>
> The writing support is specially useful for manufacturing images where
> we can use Linux to do the initial programing, consult a database to
> find out inventory information (MAC address for example) and do proper
> programing on the OTP fuses. However I also believe we shouldn't have
> this available on regular kernel images as it is easy to get a
> 'expensive paper weight'.
>
> So would you be keen to rework the patch and include a write support
> config option?

No.

Sorry but I really think such dangerous stuff never should make it's way
into any kernel which doesn't have big red and yellow signs attached to
it. And unfortunately that isn't possible.

And even if it would be possible to mark kernels as dangerous, I think
that functionality should only be part of a bootloader where it isn't 
reachable by normal userspace.

Regards,

Alexander Holler