[U-Boot] Fwd: u-boot environment variable storage

[twebb]

meant to reply to list...

>
>> Acutally, I have a system that only contains eMMC flash
>> that is formatted to hold filesystems of one sort or
>> another, so there is no spare "non-filesystem" flash
>> available for the environment.  There is also no other
>> form of NVRAM on the device.  These are the reasons I
>> asked about whether the environment could be maintained in
>> file form; I have no need to set/get environment variables
>> from userland.
>
> Where is u-boot stored then? Masked ROM, or a uP core in an
> FPGA?  As I said I have a small brain.  You can probably graft
> a R/W file system into u-boot without too much trouble if
> you need to.
>
> Matt
>

u-boot is stored as a file in a FAT32 partition of eMMC flash.  TI's
OMAP 35xx processors can boot that way (x-loader loaded first, then
x-loader loads u-boot).

Maybe I don't understand something about eMMC flash.  Can u-boot
write/read to/from a raw partition of eMMC, (i.e. not in any sort of
file form)?  I know u-boot has the ability to read from MMC devices -
can it write to them?  If so, I'm just not sure how to go about
addressing eMMC flash memory in "raw" form.  I don't see mmc_read() or
mmc_write() immplemented in the u-boot source I have (from TI OMAP 35x
SDK, u-boot-1.1.4.  Otherwise, how can u-boot support the new class of
flash storage including eMMC, eSD, and eLBA?

On the other hand, I see fatload() implemented (which seems to be
equivalent to fat_read()); is there a fat_write()?  That would solve
everything.