Specifications
For building against older versions of the MTD headers (meaning before v2.6.8-rc1) it is required to pass the
argument "MTD_VERSION=old" to make:
make MTD_VERSION=old env
The resulting binary is called fw_printenv, but actually includes support for setting environment variables
too. To achieve this, the binary behaves according to the name it is invoked as, so you will have to create a
link called fw_setenv to fw_printenv.
These tools work exactly like the U-Boot commands printenv resp. setenv You can either build these
tools with a fixed configuration selected at compile time, or you can configure the tools using the
/etc/fw_env.config configuration file in your target root filesystem. Here is an example configuration
file:
# Configuration file for fw_(printenv/saveenv) utility.
# Up to two entries are valid, in this case the redundand
# environment sector is assumed present.
#########################################################################
# For TQM8xxL modules:
#########################################################################
# MTD device name Device offset Env. size Flash sector size
/dev/mtd0 0x8000 0x4000 0x4000
/dev/mtd0 0xC000 0x4000 0x4000
#########################################################################
# For NSCU:
#########################################################################
# MTD device name Device offset Env. size Flash sector size
#/dev/mtd1 0x0000 0x8000 0x20000
#/dev/mtd2 0x0000 0x8000 0x20000
#########################################################################
# For LWMON
#########################################################################
# MTD device name Device offset Env. size Flash sector size
#/dev/mtd1 0x0000 0x2000 0x40000
14.3.29. The appWeb server hangs OR /dev/random
hangs
Question:
I try to run the appWeb server, but it hangs, because read accesses to /dev/random hang forever.
What's wrong?
Answer:
Your configuration of the Linux kernel does not contain drivers that feed enough entropy for
/dev/random. Often mouse or keyboard drivers are used for this purpose, so on an embedded
system without such devices /dev/random may not provide enough random numbers for your
application.
Workaround:
As a quick workaround you can use /dev/urandom instead; i. e. try the following commands on
your system:
# cd /dev
14.3.29. The appWeb server hangs OR /dev/random hangs 195