[U-Boot] [PATCH 0/5] Create an API for safely accessing BMP header fields

[Albert ARIBAUD]

Hi Nikita,

On Mon,  4 Feb 2013 13:39:34 +0200, Nikita Kiryanov
<nikita at compulab.co.il> wrote:

> When configuring U-Boot to display a splash image, the user is free to
> designate whatever address they see fit as the in-memory location of BMP
> file. Unfortunately, this makes it easy to place the BMP header fields in
> unaligned addresses, which will cause a data abort on architectures which
> can't handle unaligned memory accesses. What's worse, addresses which are
> supposed to be issue free (32 bit aligned addresses) actually don't work
> because of the structure of the BMP header file (the header starts with 2
> chars, followed by __u32 fields. The two chars offset the 32 bit fields away
> from proper alignment).
> 
> As a result, it is very easy to brick the board that U-Boot runs on with certain
> architectures. Once a bad address for splash image is selected and the board
> restarted, U-Boot never reaches command line, and yet the only way to prevent
> the data aborts from happening is to clear or change the environment variable
> splashimage.
> 
> While it is possible to fix the problem by compiling all relevant files with
> $(PLATFORM_NO_UNALIGNED), it is possible to handle it with finer granularity by
> creating an API for header accesses, and compiling only that with
> $(PLATFORM_NO_UNALIGNED).
> 
> This patchset creates such an API, and makes use of it wherever an in-memory BMP
> header is probed for data.

IIRC, you has submitted a fix so that BMP loads would result in
correctly aligned fields and thus no need for accessors. Why this
change of mind?

Amicalement,
-- 
Albert.