From: tnp@invalid.invalid   
      
   On 23/01/2025 22:12, Chris Green wrote:   
   > Is it simply a matter of leaving /boot on the SD card and changing /   
   > to being a USB drive or does one need to edit something in /boot   
   > somewhere?   
      
   AFAICR what you do is simply edit a file and tell it that / is not where   
   it thinks it is   
      
   But it depends on exactly what you want to happen   
      
   The boot process is as follows (I think: Others will correct If I've got   
   it wrong)   
      
   The  Pi firmware looks on the SD card for a Vfat partition, and in there   
   is a file called cmdline.txt   
      
   e.g.   
   console=serial0,115200 console=tty1 root=PARTUUID=778a9e44-02   
   rootfstype=ext4 fs   
   ck.repair=yes rootwait noswap=1   
      
   That file tells the boot loader wher the root directory is to be found   
   that it is to  grab the kernel off   
      
   the key thing is root=PARTUUID=   
      
   Now if the SD card does not have such a partition, the boot loader will   
   look to see if e.g. a USB drive has, and use that instead.   
      
   Now on whatever partition it uses as the first stage root, it will have   
   /etc/fstab   
   e.g.   
      
   proc            /proc           proc    defaults          0       0   
   PARTUUID=778a9e44-01  /boot/firmware  vfat    defaults          0       2   
   PARTUUID=778a9e44-02  /               ext4    defaults,noatime  0       1   
      
   And at this point the booting system may, if you want, mount an entirely   
   different root filesystem and carry on.   
      
   So if you edit the /etc/fstab on the SD card, and change the PARTUUID to   
   a different drive, it will mount that instead. And never touch the SD   
   card afterwards.   
      
   The easy way to do that is to boot the thing as normal, edit the fstab   
   file to match the ID of the  USB device and reboot, making sure that   
   yiou have copied everything on te root partition of the SD card to the USB.   
      
   But frankly its almost always easier to install everything on the USB   
   drive and remove the SDcard altogether.   
      
      
      
   --   
   There is something fascinating about science. One gets such wholesale   
   returns of conjecture out of such a trifling investment of fact.   
      
   Mark Twain   
      
   --- SoupGate-DOS v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)