1/// notes about altboot /// 2 3$NetBSD: README.altboot,v 1.1 2011/01/23 01:05:30 nisimura Exp $ 4 5Altboot is a functional bridge to fill the gap between a NAS product 6custom bootloader and the NetBSD kernel startup environment. Altboot 7irons out and rectifies erroneously configured HW by product 8bootloaders and prepares a sane runtime better suited for booting 9NetBSD kernels. 10 11- provides the foundation of a fast NetBSD porting cycle with functionalities 12 product bootloaders don't have. 13- facilitates a flexible and clean NetBSD implementation tailoured 14 to target HW in detail, minimizing bumpy adjustments and hacks in 15 locore asm and machdeps in very early kernel startup stage. 16- levels out differences among similar-but-not-the-same porting 17 targets to make it possible having common NetBSD kernels for them. 18- builds and hands a bootinfo list to the NetBSD kernel. 19 20Altboot is known working on two models. 21- KuroBox with a popular U-Boot as the replacement of vendor proprietary 22 23 U-Boot 1.1.4 LiSt 2.1.0 (Sep 21 2006 - 00:22:56) LinkStation / KuroBox 24 25- Synology 101g+ with vendor custom PPCboot 26 27 PPCBoot 2.0.0 (Mar 1 2005 - 15:31:41) 28 29The standard use of altboot is to invoke it with a short script from 30U-Boot/PPCboot, where the altboot image is stored in an unoccupied 128KB 31section of the target's HW NOR flash. Combined with standard 32U-Boot/PPCboot functions, it is possible to boot a NetBSD kernel off 33it right after power-on, without the help of manual intervention. Note 34that the original U-Boot/PPCboot still remains useful and altboot works 35as a functional extension for them. 36 37Altboot hands the following bootinfo records to the NetBSD/sandpoint 38kernel. 39- processor clock tick value driving MPC8241/8245. 40- serial console selection. 41- booted kernel filename and which device it was fetched from. 42- Ethernet MAC address, if target HW lacks SEEPROM to store a unit unique 43 value. 44- product family indication. 45- preloaded kernel module names (under development). 46 47 ### ### ### 48 49