PATCH: Fix MMC boot in OMAP4 xload configurations

[Sascha Hauer]

Hi Mark,

On Thu, Feb 23, 2012 at 04:53:28PM +0000, Mark Olleson wrote:
> omap4_bootsrc() always returns OMAP_BOOTSRC_UNKNOWN when an OMAP4
> xload image is built with pcm049_xload_defconfig.  This is likely to
> be the case for all OMAP4 xload configurations.
> 
> This means that when the CPU is configured to boot from MMC1 with
> boot[5:0],  xload will load the second stage boot loader from NAND
> flash (if present) rather than MMC1 as intended. 
> 
> omap4_bootsrc() reads data left behind towards the top of the SRAM by
> the ROM-based boot-loader.  This is the same SRAM into which the xload
> image is loaded.   The xload image is of a sufficient size that it
> overwrites these locations, and OMAP4_TRACING_VECTOR3 always contains
> 0.
> 
> These locations are in fact trampled by data in the BSS section of the
> image.   The single largest item in there is FILE files[MAX_FILES].
> This patch reduces the size of files[] considerably.  The image now
> JUST fits.

Sorry, this is not even a short term solution, it will probably break
very soon again.

> 
> Long term, a better solution would be to not rely on
> OMAP4_TRACING_VECTOR3, and instead use the structure passed into the
> xload by the ROM-based boot loader - which also indicates the boot
> device.     This wold allow us another 4kB of code before we overflow
> the SRAM completely.

That sounds interesting. I wasn't aware that the ROM passes a structure
into the bootloader.

Another thing is that I still have the Thumb2 patches pending which are
currently blocked by Jean-Christophe.

Jean-Christophe, please please have a look on these patches again or at
least say *what* is wrong with them so that I have a chance to rework
them.

Sascha

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