[U-Boot-Users] [PATCH] expand macros in bootargs env var for bootm command

Murray.Jensen at csiro.au Murray.Jensen at csiro.au
Thu Jun 30 16:37:28 CEST 2005

On Thu, 30 Jun 2005 15:43:53 +0200, Wolfgang Denk writes:
>You can expand all macros when building the bootargs variable like it
>is shown in all the examples in the DULG; is there any  problem  with

Quoting from the DULG:

"We can use U-Boot environment variables to store all necessary configuration

=> setenv ipaddr
=> setenv serverip
=> setenv netmask
=> setenv hostname tqm
=> setenv rootpath /opt/eldk/ppc_8xx
=> saveenv

Then you can use these variables to build the boot arguments to be passed to
the Linux kernel:

=> setenv bootargs root=/dev/nfs rw nfsroot=\$(serverip):\$(rootpath) ip=\$(ipaddr):\$(serverip):\$(gatewayip):\$(netmask):\$(hostname)::off

Note how backslashes are used to delay the substitution of the referenced
environment variables. This way, the current values of these variables get
inserted when the "bootargs" variable itself is used, i. e. when the kernel
gets booted. This allows us to simply redefine any of the variables (say, the
value of "ipaddr" if it has to be changed), and the changes will
automatically propagate to the Linux kernel."

But I found that this (or at least, an almost identical situation) simply
didn't work. Macros in the bootargs variable weren't expanded when the kernel
was booted. Maybe I've missed something?

>See section "Submitting Patches" in the README.
>There is no excuse for not reding the README.

Except that I read the README file many years ago before this section
was in there. Obviously, I need to re-read it. Cheers!
Murray Jensen, CSIRO Manufacturing & Infra. Tech.      Phone: +61 3 9662 7763
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