BootROM

I dumped MediaTek MT8125 BROM with the method below

1. build kernel with brom nvmem dt node https://github.com/TeamYogaBlade2/linux/commit/77a12e3dc2e0de7fb545651ea3d2c5ec10021caa
2. flash and boot it
3. cat /sys/bus/nvmem/devices/nvmem0/nvmem | base64 (on device) -> base64 -d > brom-mt8125-dump (on pc)

As a result, the dumped BROM was exactly the same as mediatek/MT6589WTK 1325-ATAH DTNGT126/dump-1.bin and mediatek/mt6589.bootrom.bin

❯ ls
dump-1.bin  dump-2.bin	dump-3.bin  mt6589.bootrom.bin
❯ cmp dump-1.bin dump-2.bin
dump-1.bin dump-2.bin differ: byte 1, line 1
❯ hexdump -C dump-1.bin | head
00000000  07 00 00 ea fe ff ff ea  fe ff ff ea fe ff ff ea  |................|
00000010  fe ff ff ea fe ff ff ea  fe ff ff ea fe ff ff ea  |................|
00000020  bb bb bb bb 00 00 a0 e3  00 10 a0 e3 00 20 a0 e3  |............. ..|
00000030  00 30 a0 e3 00 40 a0 e3  00 50 a0 e3 00 60 a0 e3  |.0...@...P...`..|
00000040  00 70 a0 e3 00 80 a0 e3  00 90 a0 e3 00 a0 a0 e3  |.p..............|
00000050  00 b0 a0 e3 00 c0 a0 e3  0c d0 a0 e1 00 e0 a0 e3  |................|
00000060  3b 34 00 eb 00 00 0f e1  c0 10 a0 e3 01 00 80 e1  |;4..............|
00000070  00 f0 2f e1 13 34 00 eb  74 20 9f e5 00 20 92 e5  |../..4..t ... ..|
00000080  70 30 9f e5 00 30 93 e5  08 10 43 e2 01 d0 a0 e1  |p0...0....C.....|
00000090  01 00 a0 e3 33 00 00 eb  73 34 00 eb 1c 1f 00 eb  |....3...s4......|
❯ hexdump -C dump-2.bin | head
00000000  52 45 53 56 00 00 00 00  00 00 00 00 00 00 00 00  |RESV............|
00000010  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
*
00000040  02 00 00 00 00 00 00 00  45 4d 4d 43 5f 42 4f 4f  |........EMMC_BOO|
00000050  54 00 00 00 01 00 00 00  00 02 00 00 00 00 00 00  |T...............|
00000060  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
*
00000240  00 00 00 00 00 00 00 00  42 52 4c 59 54 00 00 00  |........BRLYT...|
00000250  01 00 00 00 00 08 00 00  00 08 02 00 42 42 42 42  |............BBBB|
00000260  05 00 01 00 00 08 00 00  00 08 02 00 01 00 00 00  |................|
❯ hexdump -C dump-3.bin | head
00000000  06 00 00 ea b0 0f 10 ee  03 1f 00 e3 01 00 10 e1  |................|
00000010  00 00 00 1a 1e ff 2f e1  02 f0 20 e3 fd ff ff 0a  |....../... .....|
00000020  00 00 0f e1 c0 10 a0 e3  01 00 80 e1 00 f0 2f e1  |............../.|
00000030  04 b0 a0 e1 05 c0 a0 e1  40 00 4f e2 84 10 9f e5  |........@.O.....|
00000040  01 00 50 e1 0b 00 00 0a  7c 20 9f e5 7c 30 9f e5  |..P.....| ..|0..|
00000050  02 20 43 e0 02 20 80 e0  f8 07 b0 e8 f8 07 a1 e8  |. C.. ..........|
00000060  02 00 50 e1 fb ff ff da  0b 40 a0 e1 0c 50 a0 e1  |..P......@...P..|
00000070  50 10 9f e5 11 ff 2f e1  10 0f 11 ee 06 0b 80 e3  |P...../.........|
00000080  10 0f 01 ee 50 1f 11 ee  0f 16 81 e3 50 1f 01 ee  |....P.......P...|
00000090  00 10 a0 e3 6f f0 7f f5  01 01 a0 e3 10 0a e8 ee  |....o...........|
❯ hexdump -C mt6589.bootrom.bin | head
00000000  07 00 00 ea fe ff ff ea  fe ff ff ea fe ff ff ea  |................|
00000010  fe ff ff ea fe ff ff ea  fe ff ff ea fe ff ff ea  |................|
00000020  bb bb bb bb 00 00 a0 e3  00 10 a0 e3 00 20 a0 e3  |............. ..|
00000030  00 30 a0 e3 00 40 a0 e3  00 50 a0 e3 00 60 a0 e3  |.0...@...P...`..|
00000040  00 70 a0 e3 00 80 a0 e3  00 90 a0 e3 00 a0 a0 e3  |.p..............|
00000050  00 b0 a0 e3 00 c0 a0 e3  0c d0 a0 e1 00 e0 a0 e3  |................|
00000060  3b 34 00 eb 00 00 0f e1  c0 10 a0 e3 01 00 80 e1  |;4..............|
00000070  00 f0 2f e1 13 34 00 eb  74 20 9f e5 00 20 92 e5  |../..4..t ... ..|
00000080  70 30 9f e5 00 30 93 e5  08 10 43 e2 01 d0 a0 e1  |p0...0....C.....|
00000090  01 00 a0 e3 33 00 00 eb  73 34 00 eb 1c 1f 00 eb  |....3...s4......|
($?=0)❯ diff dump-1.bin mt6589.bootrom.bin
($?=0)❯ diff dump-1.bin ../brom-mt8125-dump

PS: dumped from Lenovo YOGA Tablet 10 Wi-Fi (b8000-f)

https://github.com/Zenofex/SoC-BootROMs/issues/38