Successful with QNAP TS-112P.

Successful with QNAP TS-112P. The script works without any problems and I was able to install Bullseye with the new kernel. Thanks for your work. Log:
[Check of the QNAP model and see if supported]
kirkwood-qnap: machine: QNAP TS219 family
DTB file: kirkwood-ts219-6281.dtb
Checking: flashcp -V
Checking: flash_erase --version
Using 'libubootenv-tool' package

[find on which MTD device partitions are currently mounted]
   spi0.0

[Dump current U-boot config']
Current U-boot bootcmd:
    uart1 0x68;cp.l 0xf8200000 0x800000 0x80000;cp.l 0xf8400000 0xa00000 0x240000;bootm 0x800000
Current U-boot bootargs:
    console=ttyS0,115200 root=/dev/ram initrd=0xa00000,0x900000 ramdisk=34816

[Prepare new 'bootcmd']
   Old: uart1 0x68;cp.l 0xf8200000 0x800000 0x80000;cp.l 0xf8400000 0xa00000 0x240000;bootm 0x800000
   New: uart1 0x68;cp.l 0xf8100000 0x800000 0xc0000;cp.l 0xf8400000 0xb00000 0x300000;bootm 0x800000;echo Kernel_legacy layout fallback;bootm 0x900000

[Prepare new 'bootargs']
   Old: console=ttyS0,115200 root=/dev/ram initrd=0xa00000,0x900000 ramdisk=34816
   New: console=ttyS0,115200 root=/dev/ram initrd=0xb00000,0xc00000 ramdisk=34816 cmdlinepart.mtdparts=spi0.0:512k@0(uboot)ro,3M@0x100000(Kernel),12M@0x400000(RootFS1),2M@0x200000(Kernel_legacy),256k@0x80000(U-Boot_Config),256k@0xc0000(NAS_Config) mtdparts=spi0.0:512k@0(uboot)ro,3M@0x100000(Kernel),12M@0x400000(RootFS1),2M@0x200000(Kernel_legacy),256k@0x80000(U-Boot_Config),256k@0xc0000(NAS_Config)

[Prepare fw_setenv script (/tmp/fw_setenv.script)]

[Dump current 'NAS config' and 'Kernel' images]
+ cat /dev/mtd5
[Resize 'NAS config' dump from 1280KB to 256KB.]
+ modprobe loop
+ losetup --show -f /tmp/mtd_nas_config.dump
+ loopdev=/dev/loop0
+ e2fsck -f -p -v /dev/loop0

          17 inodes used (13.28%, out of 128)
           0 non-contiguous files (0.0%)
           0 non-contiguous directories (0.0%)
             # of inodes with ind/dind/tind blocks: 0/0/0
          50 blocks used (4.88%, out of 1024)
           0 bad blocks
           0 large files

           6 regular files
           2 directories
           0 character device files
           0 block device files
           0 fifos
           0 links
           0 symbolic links (0 fast symbolic links)
           0 sockets
------------
           8 files
+ e2fsck -f -p -v /dev/loop0

          17 inodes used (13.28%, out of 128)
           0 non-contiguous files (0.0%)
           0 non-contiguous directories (0.0%)
             # of inodes with ind/dind/tind blocks: 0/0/0
          50 blocks used (4.88%, out of 1024)
           0 bad blocks
           0 large files

           6 regular files
           2 directories
           0 character device files
           0 block device files
           0 fifos
           0 links
           0 symbolic links (0 fast symbolic links)
           0 sockets
------------
           8 files
+ resize2fs /dev/loop0 128
resize2fs 1.46.2 (28-Feb-2021)
Resizing the filesystem on /dev/loop0 to 128 (1k) blocks.
The filesystem on /dev/loop0 is now 128 (1k) blocks long.

+ losetup -d /dev/loop0

[Concatenate first 256K of 'NAS config' with first 1MB of Kernel > /tmp/mtd_nas_config.new]

[Prepare second 1MB of kernel tail > /tmp/mtd_kernel.tail]
------------------------------------------------------------
    !!!! Warning !!!!

    Everything is fine up to now.
    Next steps will write the flash and may be subject to failures.

    It is highly recommended to perform a MTD backup and save the files
    somewhere (USB device, PC)

        cat /dev/mtd0 > /tmp/mtd0.uboot.backup
        cat /dev/mtd1 > /tmp/mtd1.kernel.backup
        cat /dev/mtd2 > /tmp/mtd2.rootfs1.backup
        cat /dev/mtd3 > /tmp/mtd3.rootfs2.backup
        cat /dev/mtd4 > /tmp/mtd4.uboot-config.backup
        cat /dev/mtd5 > /tmp/mtd5.nas-config.backup
        fw_printenv -c /tmp/fw_env.config  > /tmp/uboot_config.backup.txt
        cd /tmp
        tar cvzf mtd_backup.tgz mtd?.*.backup uboot_config.backup.txt

        # now use scp / sftp to push/pull mtd_backup.tgz on another PC.

    Be sure you will not cut the power until the end of operations.
    In case of failure, you way need to recover with a Serial Console
    to run U-boot commands

        https://www.cyrius.com/debian/kirkwood/qnap/ts-219/serial/

Continue and flash the new partitions ? (y/N)
Note: You are using --dry-run option. No flash operations will be performed if you answer 'y'.
y

[Flash 'NAS config' partition content (ie 'NAS config' + head of Kernel) (still a 'safe' op)]
(Dry run)
+ flashcp -v /tmp/mtd_nas_config.new /dev/mtd5

[Change U-boot config with new values)]
(Dry run)
+ fw_setenv -c /tmp/fw_env.config -s /tmp/fw_setenv.script

[Flash tail of the kernel in old 'Kernel' Partition]
(Dry run)
+ flashcp -v /tmp/mtd_kernel.tail /dev/mtd1

[Make a copy of /tmp/fw_env.config into /etc/fw_env.config (if not already existing)]
------------------------------------------------------------

    SUCCESS.

    Now, REBOOT !

    Notes:
    - DO NOT PERFORM A KERNEL OR SYSTEM UPDATE before the next reboot !...
      so don't wait too long.
    - Consider compressing initrd with 'xz' to optimize the size with:

        echo "COMPRESS=xz" > /etc/initramfs-tools/conf.d/compress
amouiche / qnap_mtd_resize_for_bullseye

Successful with QNAP TS-112P. #27
