This is a very brief writeup of how to upgrade the BIOS on a X1 Carbon (G1) from Linux. For more information on this topic there is always the excellent ThinkWiki.

OK, this post is more about creating the bootable USB stick needed, was too much of a chicken to try Flashrom

First, find your serial number, for querying Lenovo support (BIOS upgrade) pages.

sudo dmidecode -t system

The serial number is actually the combination of the Product Name and the Serial Number. E.g.

Handle 0x000D, DMI type 1, 27 bytes
System Information
    Manufacturer: LENOVO
    Product Name: 3460CLG
    Version: ThinkPad X1 Carbon
    Serial Number: DEXFXX
    Wake-up Type: Power Switch
    SKU Number: LENOVO_MT_3460
    Family: ThinkPad X1 Carbon

Which in my case means 3460CLG-DEXFXX … actual serial have been obfuscated, obviously. Find the Drivers & Software URL at Lenovo (again, real serial number obfuscated in URL).

Navigate to the “BIOS Update Bootable CD”, which in my case turned out to be called g6uj21us.iso. Now we need to convert the ISO to an IMG file to be able to dd it to a USB stick:

./ -o g6uj21us.img g6uj21us.iso
Booting catalog starts at sector: 20 
Manufacturer of CD: NERO BURNING ROM
Image architecture: x86
Boot media type is: harddisk
El Torito image starts at sector 27 and has 65536 sector(s) of 512 Bytes

Image has been written to file "g6uj21us.img".

The link to the Perl script is available on the ThinkWiki page, or from GitHub. Now, insert a USB stick and unmount it manually, not using Ubuntu/Gnome file manager’s eject thingy!

Write to USB, mine was at /dev/sdb BUT YOURS MIGHT NOT BE, WATCH OUT!

sudo dd if=g6uj21us.img of=/dev/sdb
65536+0 records in
65536+0 records out
33554432 bytes (34 MB, 32 MiB) copied, 16,5346 s, 2,0 MB/s

Reboot your laptop and select UEFI First in BIOS startup order, then F12 and select boot from Generic USB mass storage device. Done.

Follow the instructions in the tool to upgrade your BIOS.