Kindle firmware that uses Linuxカーネルs 2.6.10 to 3.0[1] (latest version available) Kindle 1: 1.2.1 Kindle 2: 2.5.8 Kindle DX: 2.5.8 Kindle Keyboard: 3.4.3 Kindle 4, 5: 4.1.4 Kindle Touch: 5.3.7.3 Kindle Paperwhite (1st gen): 5.6.1.1 Kindle Paperwhite (2nd, 3rd & 4th gen), Kindle 7, 8, 10, Voyage, Oasis 1, 2, 3: 5.12.4[2] Kindle 1: Marvell Xscale PXA255 400 MHz, ARM9 Kindle 2, DX: Freescale i.MX31 53