[U-Boot] BSS footprint of FAT very high - SPL issues

[Wolfgang Denk]

Dear Ulf Samuelsson,

In message <4E6FCDB3.1080202 at telia.com> you wrote:
>
> > In mainline U-Boot we tend to use nand_spl instead.  There should be
> > no need for such externel, out-of-tree code.

In the mean time, code has been reorganized, generalized and improved.

> I am not aware of a single at91 user which uses nand_spl.  Are you?

Well, AT91 support is pretty poor in general, compared to other SoC
families.  This is not exactly a problem of U-Boot.

> Does nand_spl support at91?

The design of the SPL code is not specific to any processor or
architecture.  Adding AT91 support is not more and not less difficult
than for any other SoC.

> Does it support loading from SPI Flash, Dataflash, EEPROM and SD-Card?

EEPROM?  I haven't seen a device booting U-Boot (or Linux) from an
EEPROM yet - but if you like, you can add such suppport, too.

Yes for the others, plus NAND and NOR.

> Does is support loading WinCE instead of U-Boot?

Yes, this can be supported.

> Does it support loading other stuff?

Yes, it does.  Tested for example with loading and starting a Linux
kernel.

> Is there anyone outside the u-boot core members that care what is used 
> to load u-boot?

Yes.  Customers and other end users for example, who don;t like having
to maintain unnecessary software packages and keeping tools and
scripts in place to build them; people who are interested in minimal
boot times, etc.

> Anyway, your comment deviates from the real issue.
> The environment is stored on an SPI device, and U-boot reads the environment
> before it initializes the SPI. This is a bug, that needs fixing.

The bug is in your configuration.  If you load U-Boot from a SPI
flash, you can simply load the environment with it, in a single
operation.

> I see just a few choices.

I can see a number more options.

> 1. Forbid anyone to store the environment in an SPI flash.
> 2. Initialize the SPI before reading the environment
> 3. Make the environment available without initializing the SPI first.

None of these are needed.

> I assume the same problem is with the I2C, SD-Card interface, which may 
> need to be initialized
> before the environment is read, if the environment happens to use such 
> an interface.

It's just a configuration.  It is not a problem.  At least not for us.

Best regards,

Wolfgang Denk

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