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Driver porting development notes

Vendor's open-source kernel patches

Access the GPL'd kernel patches inside the UnRAID firmware, without installing the software:

wget https://unraid-dl.sfo2.cdn.digitaloceanspaces.com/stable/unRAIDServer-6.12.2-x86_64.zip
unzip unRAIDServer-6.12.2-x86_64.zip -d unRAIDServer
cd unRAIDServer
unsquashfs -d patches bzfirmware src

There are patches to multiple drivers, but we are only interested in the changes needed for md_unraid functionality:

  1. adds md_unraid and unraid.c to drivers/md/
  2. patches md Kconfig / Makefile
  3. patches raid6 algos.c
  • replaces normal md driver, md stays as module
  • disables all other md raid support, and a bunch of other DM features
  • otherwise md changes are pretty self-contained, patches should apply easily(?) to other kernel versions

release 7.1.4

  • based on kernel 6.12.24
  • patches apply to ubuntu lts 6.8.0 (with offsets), but:
    • bdev_file_open_by_path - requires 6.9+
    • blk_alloc_disk / BLK_FEAT_WRITE_CACHE - requires 6.11+
  • HWE kernel possible? currently 6.11, soon 6.14

release 7.0.1

  • based on kernel 6.6.78
  • has no functional changes compared to 7.1.4, it is only rebased on newer kernel version
  • patches apply to ubuntu lts 6.8.0 (with offsets)

Kernel issues

  • Unlike unraid, Ubuntu has CONFIG_UBSAN=y enabled and this is causing array-index-out-of-bounds kernel errors/warnings in dmesg for all array operations.
    • we disable CONFIG_UBSAN when building the dkms module (though this is probably really a problem with unraid code)