run: create -F option to run base64 encoded command after busybox init

Fix ./run -h which was showing the build help instead.

README.adoc

@@ -896,7 +896,7 @@ It is kind of random: if you just `insmod` manually and then immediately `./rung
 But this fails most of the time: shell 1:
 
 ....
-./run -a arm -f 'lkmc_eval="insmod /hello.ko"'
+./run -a arm -F 'insmod /hello.ko'
 ....
 
 shell 2:
@@ -983,7 +983,7 @@ So once we find the address the first time, we can just reuse it afterwards, as
 Do a fresh boot and get the module:
 
 ....
-./run -f 'lkmc_eval="/pr_debug.sh;insmod /fops.ko;/poweroff.out"'
+./run -F '/pr_debug.sh;insmod /fops.ko;/poweroff.out'
 ....
 
 The boot must be fresh, because the load address changes every time we insert, even after removing previous modules.
@@ -1747,7 +1747,20 @@ although `-E` is smarter:
 
 so you should almost always use it, unless you are really counting each cycle ;-)
 
-This method prevents the BusyBox' init from launching a shell, so you cannot interact with the system afterwards. If you also want that, use: <<init-busybox>>.
+This method replaces BusyBox' init completely, which makes things more minimal, but also has has the following consequences:
+
+* `/etc/fstab` mounts are not done, notably `/proc` and `/sys`, test it out with:
++
+....
+./run -E 'echo asdf;ls /proc;ls /sys;echo qwer'
+....
+* no shell is launched at the end of boot for you to interact with the system. You could explicitly add a `sh` at the end of your commands however:
++
+....
+./run -E 'echo hello;sh'
+....
+
+The best way to overcome those limitations is to use: <<init-busybox>>
 
 If the script is large, you can add it to a gitignored file and pass that to `-E` as in:
 
@@ -1799,13 +1812,23 @@ but why not just use your super simple and effective `/poweroff.out` and be done
 [[init-busybox]]
 === Run command at the end of BusyBox init
 
-If you rely on something that BusyBox' init set up for you like networking, you could do:
+If you rely on something that BusyBox' init set up for you like `/etc/fstab`, this is the method you should use:
 
 ....
-./run -f 'lkmc_eval="insmod /hello.ko;wget -S google.com;poweroff.out;"'
+./run -F 'echo asdf;ls /proc;ls /sys;echo qwer'
 ....
 
-The `lkmc_eval` option gets evaled by our default `S98` startup script if present.
+After the commands run, you are left on an interactive shell.
+
+The above command is basically equivalent to:
+
+....
+./run -f 'lkmc_eval="insmod /hello.ko;poweroff.out;"'
+....
+
+where the `lkmc_eval` option gets evaled by our default `S98` startup script if present.
+
+However, `-F` is smarter and uses `base64` encoding, much like `-E` vs `-e`, so you will just use `-F` most of the time.
 
 Alternatively, add them to a new `init.d` entry to run at the end o the BusyBox init:
 

rootfs_overlay/etc/init.d/S98

@@ -1,7 +1,8 @@
 #!/bin/sh
 echo "hello S98"
 if [ -n "$lkmc_eval" ]; then
-  echo "$lkmc_eval"
   eval "$lkmc_eval"
+elif [ -n "$lkmc_eval_base64" ]; then
+  eval "$(printf "$lkmc_eval_base64" | base64 -d)"
 fi
 exit 0

run

@@ -31,7 +31,7 @@ tmux_args=
 # just to prevent QEMU from emitting a warning that '' is not valid.
 trace_enable=pr_manager_run
 vnc=
-while getopts a:c:DdE:e:f:G:ghIiKkm:T:U:uVx OPT; do
+while getopts a:c:DdE:e:F:f:G:ghIiKkm:T:U:uVx OPT; do
   case "$OPT" in
     a)
       arch="$OPTARG"
@@ -52,10 +52,13 @@ while getopts a:c:DdE:e:f:G:ghIiKkm:T:U:uVx OPT; do
       lkmc_eval="$OPTARG"
       ;;
     e)
-      extra_append="$extra_append $OPTARG"
+      extra_append="${extra_append} ${OPTARG}"
+      ;;
+    F)
+      extra_append_after_dash="${extra_append_after_dash} lkmc_eval_base64=\"$(printf "${OPTARG}" | base64)\""
       ;;
     f)
-      extra_append_after_dash="$extra_append_after_dash $OPTARG"
+      extra_append_after_dash="${extra_append_after_dash} ${OPTARG}"
       ;;
     G)
       gem5opts="$OPTARG \\
@@ -65,7 +68,7 @@ while getopts a:c:DdE:e:f:G:ghIiKkm:T:U:uVx OPT; do
       gem5=true
       ;;
     h)
-      cat build-usage.adoc 1>&2
+      cat run-usage.adoc 1>&2
       exit
       ;;
     I)

run-usage.adoc

@@ -19,6 +19,8 @@
                       Only options that come before the `-`, i.e. "standard"
                       options, should be passed with this option.
                       Example: `./run -a arm -e 'init=/poweroff.out'`
+|`-F` |`CMDSTR`      |Much like `-f`, but base64 encods the string.
+                      Mnemonic: `-F` is to `-f` what `-E` is to `-e`.
 |`-f` |`CLI_OPTIONS` |Pass an extra Linux kernel command line options,
                       add a dash `-` separator, and place the options after the dash.
                       Intended for custom options understood by our `init` scripts,