i've made some progress.
using the uimage mtdsplit, i now get the partitions created!
9 fixed-partitions partitions found on MTD device MT7621-NAND
Creating 9 MTD partitions on "MT7621-NAND":
0x000000000000-0x000000080000 : "Bootloader"
0x000000080000-0x000000100000 : "Config"
0x000000100000-0x000000140000 : "factory"
0x000000140000-0x000000180000 : "Config2"
0x000000180000-0x000002980000 : "sysv"
2 uimage-fw partitions found on MTD device sysv
Creating 2 MTD partitions on "sysv":
0x000000000000-0x0000010a0000 : "kernel"
0x0000010a0000-0x000002800000 : "ubi"
0x000002980000-0x000004980000 : "private"
0x000004980000-0x000007180000 : "firmware2"
0x000007180000-0x000007780000 : "mydlink"
0x000007780000-0x000008000000 : "reserved"
but now failing to get the partition to automatically attach, with the error "no valid UBI magic":
no valid UBI magic found inside mtd6
rtc-pcf8563 0-0051: hctosys: unable to read the hardware clock
VFS: Cannot open root device "(null)" or unknown-block(0,0): error -6
Please append a correct "root=" boot option; here are the available partitions:
1f00 512 mtdblock0
(driver?)
1f01 512 mtdblock1
(driver?)
1f02 256 mtdblock2
(driver?)
1f03 256 mtdblock3
(driver?)
1f04 40960 mtdblock4
(driver?)
1f05 17024 mtdblock5
(driver?)
1f06 23936 mtdblock6
(driver?)
1f07 32768 mtdblock7
(driver?)
1f08 40960 mtdblock8
(driver?)
1f09 6144 mtdblock9
(driver?)
1f0a 8704 mtdblock10
(driver?)
Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)
Rebooting in 1 seconds..
hoping this is a matter of cleaning out my cmdline arguments now!