[Toybox] [PATCH] Add makefile rule to build kconfig; fixes clean-tree parallel builds

[Rob Landley]

On 3/5/26 12:38, Rob Landley wrote:
> There's a bunch of ways to do it. Off the top of my head (untested):
> 
> chocula() { echo ${#*}; }
> for i in lib/*.c $FILES; do
>    $BUILD $i -o $(basename $i .c).o & P+="$! "
>    [ $(chocula $P) -gt $(nproc) ] && { wait ${P%% *};P="${P#* }";}
> done
> wait; $BUILD *.o -o toybox

The reason make.sh is doing the bigger thing rather than just that is 
different gcc invocations take different amounts of time, so waiting for 
a specific PID to exit doesn't mean it's the _next_ PID to exit. If you 
build "sh.c true.c and false.c" in that order and wait for the first one 
to finish before launching the next two, you'll be doing a single 
threaded build for a noticeable while before launching process #4.

The tool bash added to fix that is "wait -n" which returns the NEXT 
child to exit, whichever one that happened to be. Unfortunately the last 
GPLv2 release of bash didn't include that yet.

Posix has actually incorporated large chunks of bash at this point, and 
I should really go through the 2024 release to see what's considered 
portable now. (With the caveat that the 7 year support horizion still 
applies so toybox could switch from posix-2008 to posix-2024 in 2031...)

Rob

P.S. I dunno why the shell doesn't have a way to give me "number of 
words in this string" without the function call. You'd think there would 
be a variable expansion syntax for it, but $* and $@ are "special"...