Am 14.08.2014 22:53, schrieb Tom Rini:
On Thu, Aug 14, 2014 at 01:50:31PM -0600, Stephen Warren wrote:
[snip]
uenv.txt is the opposite; it's very U-Boot specific, and more about
internal implementation details of U-Boot. In particular, I only see
a use-case for uenv.txt on systems that have nowhere to store the
U-Boot environment other than in some filesystem. That's the reason
the RPi port loads uenv.txt, so the environment can be modified
somehow. Perhaps there's an ENV_IS_IN_FAT that could be used instead
on the Pi? For example, none of the Tegra boards use uEnv.txt since
"saveenv" to flash works there.
Even with ENV_IS_IN_FAT you need to be in U-Boot to modify the
environment (fw_setenv/printenv should be adaptable easily enough I
would hope, but aren't today). uEnv.txt is the way for a user to pop
the SD card into their PC, tweak the env as needed (or fiddle some
bits), eject the card and boot their target.
Yes, many "developers" today (those which do buy development boards) are
having problems to use a serial which most of the time is needed to
access the u-boot command line. The reasons are various, most devices
people do use don't have a serial anymore, the voltage of the serial
changes every few years (12, 5, 3.3 and now 1.8 Volt), sometimes a
nullmodem (just 3 wires) is needed, ...
Whatever the reason is, sometimes it can be very hard to access the
u-boot command line. But most are able to modifying or create a file on
disk. ;)
Regards,
Alexander Holler
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