[U-Boot] quoting semicolons inside nested "run" scripts?

[Joe Buehler]

I am having difficulties getting a semicolon into the LINUX kernel's
mtdparts command line parameter.

I want to do something like this:

bootcmd=run aaa
aaa=run bbb
bbb=run linux
linux=blah blah blah ${mtdparts}
mtdparts=mtdparts=blah1;blah2

I cannot figure out the quoting to get "blah2" passed to the kernel.  I
have tried various things but it always gets stripped.

Joe Buehler