more emergency boot tips

howto/new-machine-cymru.md

@@ -234,12 +234,45 @@ computer** (or, rather, you'll upload it to the server) which will be
 slow as hell, yes.
 
 If you are booting a grml image, you should probably add the following
-options to the Linux commandline:
+options to the Linux commandline (to save some typing, select the
+`Boot options for grml64-full` -> `grml64-full: Serial console`:
 
-    console=ttyS0,115200n8 ssh
+    console=tty1 console=ttyS0,115200n8 ssh grml2toram
 
-This will activate the serial console and start an SSH server with a
-random password.
+This will:
+
+ 1. activate the serial console
+ 2. start an SSH server with a random password
+ 3. load the grml squashfs image to RAM
+
+Once the system boots (and it will take a while, as parts of the disk
+image will need to be transfered): you should be able to login through
+the serial console instead. It should look something like this after a
+few minutes:
+
+    [  OK  ] Found device /dev/ttyS0.
+    [  OK  ] Started Serial Getty on ttyS0.
+    [  OK  ] Started D-Bus System Message Bus.
+
+
+    grml64-full 2020.06 grml ttyS0
+
+    grml login: root (automatic login)
+
+    Linux grml 5.6.0-2-amd64 #1 SMP Debian 5.6.14-2 (2020-06-09) x86_64
+    Grml - Linux for geeks
+    
+    root@grml ~ # 
+
+From there, you have a shell and can do magic stuff. Note that the ISO
+is still necessary to load some programs: only a minimal squashfs is
+loaded. To load the entire image, use `toram` instead of `grml2ram`,
+but note this will transfer the *entire* ISO image to the remote
+server's core memory, which can take a long time depending on your
+local bandwidth.
+
+TODO: timings. note how long each step take so we have expectations in
+emergency situations.
 
 ### Serial console access