[U-Boot] FAT12 regression after 8d48c92b45aea91e2a2be90f2ed93677e85526f1

[Heiko Schocher <hs@denx.de>]

Hello Oleksandr,

added Stefan and Tom to cc...

Am 26.01.2017 um 00:25 schrieb Oleksandr Tymoshenko:
> Hello,
>
> U-Boot 2017.01 and master branch is broken on BeagleBone Black
> with boot partition formatted as FAT12, it hang after printing "Loading
> u-boot.img" message. I bisected regression to this patch:
>
> http://lists.denx.de/pipermail/u-boot/2016-December/276305.html

Yep, I detected this issue for another am335x based board, too,
see thread here:'
http://lists.denx.de/pipermail/u-boot/2017-January/279078.html

But I did not found time to look into it...

> This code simplification is not going to work on architectures
> with strict alignment requirements:
>
> +               ret = FAT2CPU16(*(__u16 *)(mydata->fatbuf + off16));
>
> fatbuf is a pointer to __u8 and off16 can take any values so
> mydata->fatbuf + off16 is not guaranteed to be 16-bits aligned
> and 16-bit access to non-aligned address will cause exception.

Good explanation! Thanks!

bye,
Heiko
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