quirks

DSM booting quirks

List of known quirks (in a recommended to be read order):

1. Synology & GPL

   • Type: information
   • Understood: yes
   • Loader impact: N/A
   • Kernel options: N/A

2. Custom kernel params

   • Type: information
   • Understood: yes
   • Loader impact: N/A
   • Kernel options: N/A

3. Disk types

   • Type: information
   • Understood: yes
   • Loader impact: N/A
   • Kernel options: N/A

4. Kernel cmdline validation

   • Type: integrity verification
   • Understood: yes, not verified
   • Loader impact: LKM shim
   • Kernel options: all custom ones

5. Synoboot location

   • Type: operation parameter
   • Understood: yes
   • Loader impact: LKM shim
   • Kernel options: vid=, pid=, synoboot_satadom=

6. Error 13

   • Type: operation parameter
   • Understood: yes
   • Loader impact: kernel binpatch, LKM shim
   • Kernel options: vid=, pid=, synoboot_satadom=

7. Ramdisk checksum

   • Type: integrity verification
   • Understood: yes
   • Loader impact: kernel binpatch
   • Kernel options: N/A

8. boot_params Validation

   • Type: integrity verification
   • Understood: partially
   • Loader impact: kernel binpatch
   • Kernel options: N/A

9. Serial port swapping

   • Type: operation parameter
   • Understood: yes
   • Loader impact: LKM shim (hw version dependent)
   • Kernel options: N/A

10. Serial port muting

    • Type: operation parameter
    • Understood: partially
    • Loader impact: LKM shim (hw version dependent)
    • Kernel options: N/A

11. Platform management unit

    • Type: hw feature
    • Understood: no
    • Loader impact: LKM emulator
    • Kernel options: N/A

12. Hardware manufacturer's BIOS

    • Type: hw feature, integrity verification
    • Understood: yes
    • Loader impact: LKM emulator
    • Kernel options: N/A

13. Custom RTC

    • Type: hw feature
    • Understood: yes
    • Loader impact: LKM emulator
    • Kernel options: N/A

14. Hardware Monitor (hwmon)

    • Type: hw feature
    • Understood: yes
    • Loader impact: LKM emulator
    • Kernel options: N/A

15. Low-level Firmware update

    • Type: hw feature
    • Understood: yes
    • Loader impact: LKM shim or user-mode workaround
    • Kernel options: N/A

16. PCI configuration

    • Type: hw feature, sanity check
    • Understood: yes
    • Loader impact: LKM emulator
    • Kernel options: N/A

Generic notes

Current mysteries

See mysteries file which contains bits-and-pieces of information about some things which aren't known enough to warrant a file.

Kernel binary patching

Some quirks ("Loader impact: kernel binpatch") require the kernel image to be patched. This is because a given check happens before any module can be loaded and Synology doesn't share full GPL sources (the code is full of #ifdef MY_ABC_HERE) so a simple patch to the kernel is not possible.

The only option we see is binary patching. However, while it's possible:

• It isn't as easy as one may expect (and the patch part is just the tip of an iceberg)
• Binary patching must be done on uncompressed image
  • After patching the kernel needs to recompressed (or we should say partially rebuilt)
  • This is a complex process requiring custom tooling.