[E3-hacking] Config / content filesystem

[David Given]

The E3 is based on an ARM reference design, isn't it? What's the
feasibility of emulating one?

On Wed, 24 Apr 2019 at 11:46, Ralph Corderoy <ralph at inputplus.co.uk> wrote:

> Hi Nick,
>
> > > That should be possible as you have the files, now without their 16
> > > bytes per 512 bytes overhead.  You need to work out how many blocks
> > > to erase based on the size of each file you're trying to put back.
> > > IIRC I pointed out a block is the unit of erasure and it's 16 KiB.
> >
> > So e3-nand.0 is 3584 KB so how many blocks go into it…? so how many
> > times dose 16KB going in to 3584KB…?? I don’t know..?? I can’t divide.
> > Iam a bit ok on Add not brilliant at Times but can’t do Divide.
>
> Having stripped the excess OOB data, I have these sizes for each file in
> bytes.
>
>      3670016  e3-nand-backup.0
>       262144  e3-nand-backup.1
>       262144  e3-nand-backup.2
>       262144  e3-nand-backup.3
>     28311552  e3-nand-backup.4
>       786432  e3-nand-backup.5
>
> You're right, 3,670,016 B is 3,584 KiB because
>     3,670,016 / 1,024 = 3,584
> so 1,024 goes into 3,670,016 exactly 3,584 times.
>
> But the size of the erase block is 16 KiB which is
>     16 * 1,024 = 16,384
> so we want to know how many times 16,384 goes into 3,670,016.
>     3,670,016 / 16,384 = 224
> 224 is what you worked out in your other email.
>
> Taking those six sizes above and repeating the same sum gives
>
>      3,670,016 / 16,384 =   224
>        262,144 / 16,384 =    16
>        262,144 / 16,384 =    16
>        262,144 / 16,384 =    16
>     28,311,552 / 16,384 = 1,728
>        786,432 / 16,384 =    48
>
> Now I haven't been carefully following along how to extract
> e3-nand-backup.* in the first place, and how to write them back.
> I'm aware there's a script involved and a command where one of the
> parameters is the number of 16 KiB blocks to erase.  Hopefully, plugging
> in those numbers above for each of the matching areas will work, but
> it's your responsibility whether to go ahead as you're the one actually
> doing all this;  I've just been sitting at a keyboard.  :-)
>
> --
> Cheers, Ralph.
>
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