minicom in Ubuntu has several file transfer protocols preconfigured after installation and some tools implementing these protocols can be installed as a recommended package along with minicom package installation. One of preconfigured transfer protocols is kermit, but the setting in minicom for this protocol refers to nonexistent file in Ubuntu 20.04 and there are no packages with such file in this version of Ubuntu.

ckermit package is present in Ubuntu 18 and 21, but it was not included in Ubuntu 20. gkermit can be used instead. Both packages contain programs implementing kermit protocol, but these programs have slightly different command-line options and can not be used interchangeably in minicom settings.

To use minicom with gkermit, install it first and then set the following configuration in File transfer protocols menu in minicom:

| J  gkermit    /usr/bin/gkermit -iXs          Y    U    N       Y       N    |
| K  gkermit    /usr/bin/gkermit -iXr          Y    D    Y       Y       N    |

Here I added gkermit to empty slots J and K, but existing settings for kermit can be replaced as well.

Lets check how it works using U-Boot in QEMU as a test platform. Start QEMU with U-Boot image

qemu-system-arm -machine virt -bios u-boot.bin -serial pty

and connect to running machine with minicom

minicom -D /dev/pts/5

I will use a test file to transfer it to U-Boot and then verify that the file is written to memory correctly.

$ hexdump -C testfile
00000000  48 65 6c 6c 6f 2c 20 57  6f 72 6c 64 21 0a        |Hello, World!.|
0000000e

Switch to U-Boot console, start file loading and then select Send file and gkermit options from minicom menu. U-Boot will show the memory address where the file was written and also its size.

=> loadb
## Ready for binary (kermit) download to 0x40200000 at 115200 bps...
CACHE: Misaligned operation at range [40200000, 4020000e]
## Total Size      = 0x0000000e = 14 Bytes
## Start Addr      = 0x40200000

And here is the memory contents:

=> md 0x40200000
40200000: 6c6c6548 57202c6f 646c726f 00000a21  Hello, World!...
40200010: 00000000 00000000 00000000 00000000  ................