[U-Boot] Master branch broken for omap4_panda (SPL_BUILD)

From: Wolfgang Denk <wd@denx.de>
To: u-boot@lists.denx.de
Subject: [U-Boot] Master branch broken for omap4_panda (SPL_BUILD)
Date: Tue, 04 Oct 2011 20:05:16 +0200	[thread overview]
Message-ID: <20111004180517.06D4318E5B42@gemini.denx.de> (raw)
In-Reply-To: <4E8B282A.8040301@ti.com>

Dear Aneesh V,

In message <4E8B282A.8040301@ti.com> you wrote:
>
> > All file system code has been designed and implemented to run AFTER
> > relocation.  Access to a FAT file system is not supposed to happen
> > from SPL code.
...
> OMAP has traditionally supported booting from the FAT partition of an
> external SD card. The ROM code can pick up the SPL from the FAT
> partition and SPL should pick up u-boot from there too. Some of our
> boards like OMAP4 Panda have only an SD slot for non-volatile memory
> and no flash memory installed. Of course we could use the SD card in
> raw mode. But the FAT mode is much more convenient for many users. If
> FAT is not supported in SPL, it will be a major regression compared to
> x-loader and a show-stopper for us.

I understand this, and you may have noted that I did not NAK the
patch.  I just want to point out that what you are doing is pretty
dangerous, and there are no seat-belts.

> I have submitted a patch to fix the problem reported in this thread and
> FAT boot is working fine again.

For now.  But please expect that the next breakage may happen any
time, and there is no guarantee that it can be fixed as easily.

> However, I am worried about the increasing footprint of SPL. The main
> contributors are MMC and FAT. x-loader, with all it's short-comings,
> does the same job with a smaller footprint. ...

Why is this the case?  I doubt they use other FAT code, or do they?
What about MMC?

>                                         ... NAND has a custom driver
> for SPL while MMC and FAT doesn't have. I don't think it's practical
> either. However, I wonder if these drivers could be scaled down in size
> for SPL with some '#ifdef CONFIG_SPL_BUILD's. I wish if somebody could
> look into this.

Do you have exact numbers of the sizes for the MMC, FAT and NAND code
in x-loader compared to SPL U-Boot?  And what are for example the
restrictions of (V)FAT support in x-loader?

Best regards,

Wolfgang Denk

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