[U-Boot] [PATCH 1/4] common: imx: Implement generic u-boot.nand target

[Marek Vasut]

Dear Tom Rini,

> On Tue, Feb 26, 2013 at 12:33:52PM +0100, Beno??t Th??baudeau wrote:
> > On Tuesday, February 26, 2013 8:19:42 AM, Marek Vasut wrote:
> > > Dear Beno??t Th??baudeau,
> > > 
> > > > Dear Scott Wood,
> > > > 
> > > > On Tuesday, February 26, 2013 12:07:25 AM, Scott Wood wrote:
> > > > > On 02/25/2013 05:03:30 PM, Marek Vasut wrote:
> > > > > > Dear Scott Wood,
> > > > > > 
> > > > > > > So maybe we need a more general (but optional)
> > > > > > > CONFIG_BUILD_TARGET.
> > > > > > 
> > > > > > Can you elaborate?
> > > > > 
> > > > > Same as CONFIG_SPL_TARGET, but not SPL-specific.  Basically a way
> > > > > for a board config file to add to $(ALL-y).
> > > > > 
> > > > > > > So each one would set the appropriate CONFIG_BUILD_TARGET for
> > > > > > 
> > > > > > whatever
> > > > > > 
> > > > > > > needs to get built, and then something like CONFIG_NAND_IMAGE
> > > > > > > could hold the image name that should be linked to produce a
> > > > > > > standard u-boot-nand.bin output.
> > > > > > 
> > > > > > Yea, sounds reasonable. But why call it CONFIG_ , it can't be
> > > > > > stored in the
> > > > > > board.h files, it has to be somewhere in the Makefile hierarchy.
> > > > > 
> > > > > Why can't it go in the board.h files?
> > > > 
> > > > We could do all that, but should we? As I said to Marek, I think that
> > > > it's a big mistake to omit the SPL here. The only other solution to
> > > > get a reliable boot would be the DBBT, but it's very hard to use in
> > > > real life, away from a production line. The SPL is really easy to
> > > > enable here, and it's only a matter of time before someone gets
> > > > bitten by this lack of reliability, so why not just do things right?
> > > > The boot time and footprint of an SPL would really be negligible,
> > > > and it's not because other implementations omit both SPL and a valid
> > > > DBBT that U-Boot should do the same.
> > > 
> > > I'm not against SPL, but then we're starting to drift away from the
> > > whole idea
> > > of generating u-boot-nand.bin or similar image. Being able to generate
> > > u-boot-
> > > nand.bin or u-boot-sd.bin etc ... on a per-CPU basis (since this is CPU
> > > specific) is the ultimate goal here, whatever is embedded in the image.
> > 
> > OK, I didn't know that this was your goal here. If the contents of the
> > image do not matter, then my u-boot-with-nand-spl.imx could be renamed
> > into your u-boot-nand.bin with the appropriate FCB header, and
> > CONFIG_SPL_TARGET could be changed to something more generic as Scott
> > explained.
> 
> I wonder how the rules start looking.  In the end, some way to say "Here
> is the image to write to NAND, called u-boot-nand.bin" which will have
> whatever board needs (say spl/u-boot-spl.bin + some header attached
> followed by pad, followed by u-boot.img).  And also allow for
> u-boot-nand.bin to be what someone else needs (say a different header on
> u-boot-spl.bin), etc.

They'd be CPU specific rules, so that depends on the CPU really.

Best regards,
Marek Vasut