MX-760HD ROMFSExtraction

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Here's how to extract a ROMFS filesystem image file from a firmware package file (.pkg) and to repackage a modified firmware into a ROMFS file and back to a firmware pkg file.

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Extraction

If you are starting from a .pkg firmware file then you need to strip the headers and decompress the ROMFS: 

   dd bs=108 if=mvix-fw-1.1.17.pkg skip=1 | gunzip > mvix-fw-1.1.17.romfs

This file contains a complete filesystem. You can look inside the file system (readonly) by mounting it. You may need to be root to do this: 

   mkdir romfs.mountpoint
   mount -o loop -t romfs mvix-fw-1.1.17.romfs romfs.mountpoint
   cd romfs.mountpoint
   ls -l

Now you can have a look around. It's all read only, because you are still actually inside the firmware file.


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(Re)Packaging

To make changes to the firmware, you need to copy it and then repack it once the changes are made. 

   cp -a -r romfs.mountpoint romfs.mycopy
   cd romfs.mycopy

Now you can edit files. Interesting places to look are:

  • etc/ - contains setup files. you can change the passwords in etc/shadow - use /usr/sbin/grub-md5-crypt to create a new password.
  • usr/curacao/ - contains the GUI files - images etc..


Now that you've made your changes, you need to repack it into a ROMFS and then into a .pkg firmware file. 

   genromfs -V "mambo" -d romfs.mycopy -f myfw.romfs

(You can get genromfs from: http://romfs.sourceforge.net)

Finally, pack the ROMFS into a .pkg file using makeFirmware.pl. 

   perl makeFirmware.pl myfw.romfs -o myfw.pkg

You can now load this onto your player via the GUI.

Cygwin notes: genromfs compiles and works fine under cygwin, for extracting the romfs, perform a Google search for "romfs-tools.zip"

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