1/// notes about altboot /// 2 3$NetBSD: README.altboot,v 1.11 2012/04/26 19:59:36 phx 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 at least these models: 21 22- KuroBox or LinkStation with a popular U-Boot as replacement of 23 the vendor's proprietary one 24 25 U-Boot 1.1.4 LiSt 2.1.0 (Sep 21 2006 - 00:22:56) LinkStation / KuroBox 26 27- Synology 101g+ with vendor custom PPCboot 28 29 PPCBoot 2.0.0 (Mar 1 2005 - 15:31:41) 30 31- Synology 106j, 207, 407e with vendor custom PPCboot 32 33 PPCBoot 2.0.0 (Jan 30 2007 - xx:xx:xx) 34 35- D-Link DSM-G600 with heavily restricted vendor custom U-Boot 36 37 U-Boot 0.2.0 (May 26 2005 - 19:38:32) 38 39- QNAP TS-101 (V200) with vendor custom U-Boot 40 41 U-Boot 1.1.2 (Aug 28 2005 - 13:37:25) QNAP System, Inc. 42 43- Iomega StorCenter with vendor custom U-Boot 44 45 U-Boot 1.0.0 (Sep 2 2005 - 14:49:11) 46 47- Allnet 6250 and compatible with restricted vendor custom PPCboot 48 49 PPCBoot 2.0.0-A9 (Feb 13 2006 - 14:56:11) 50 51- KURO-BOX/T4 vendor custom U-Boot 52 53 U-Boot 2009.06-BUFFALO-svn1376 (Jul 11 2009 - 04:11:01) KURO-NAS/T4 54 55The standard use of altboot is to invoke it with a short script from 56U-Boot/PPCboot, where the altboot.bin image is stored in an unoccupied 128KB 57section of the target's HW NOR flash. Combined with standard 58U-Boot/PPCboot functions, it is possible to boot a NetBSD kernel off 59it right after power-on, without the help of manual intervention. Note 60that the original U-Boot/PPCboot still remains useful and altboot works 61as a functional extension for them. 62 63In case the firmware was crippled by the vendor so that it only boots 64Linux U-Boot images (D-Link, Synology 2007), you can still use altboot by 65overwriting the Linux kernel with altboot.img. 66 67Altboot passes the following bootinfo records to the NetBSD/sandpoint 68kernel: 69- processor clock tick value driving MPC8241/8245. 70- serial console selection. 71- booted kernel filename and which device it was fetched from. 72- Ethernet MAC address, if target HW lacks SEEPROM to store a unit unique 73 value. 74- product family indication. 75- preloaded kernel module names (under development). 76 77When no arguments are given, altboot defaults to boot a kernel called 78"netbsd" from the root partition of the first disk in multiuser mode. 79 80Boot arguments may be passed in three ways: 81- On the command line, directly after the "go 0x1000000" command. 82- From the U-Boot "bootargs" environment variable, when started by "bootm". 83- By entering the interactive mode. 84 85The following boot arguments are recognized: 86- multi boot into multiuser 87- auto boot into multiuser 88- single boot into singleuser 89- ask ask for boot device 90- ddb drop into the kernel debugger 91- userconf change configured devices 92 93The following boot flags are recognized: 94- norm boot normally 95- quiet boot quietly 96- verb boot verbosely 97- silent boot silently 98- debug boot with debug output 99 100Additionally the special argument "altboot" is recognized, which replaces 101the actually running altboot program with the loaded binary file and 102restarts itself. Mainly useful for altboot testing. 103 104Multiple arguments may be specified at once, although not all combinations 105make sense. The format of an altboot command line is: 106 107 [[<bootargs> ...] <devicename>:[<bootfile>] ...] 108 109Multiple boot devices and/or paths may be specified, which are booted one 110after another until success. When no boot device is specified altboot tries 111to boot from all disk devices with a valid NetBSD disklabel, starting with 112unit 0. 113 114The following device names are supported: 115- tftp boot from TFTP (address retrieved by DHCP) 116- nfs boot from NFS (address retrieved by DHCP) 117- wd[N[P]] boot from disk N, partition P, defaults to wd0a 118- mem boot from memory 119 120For tftp and nfs the bootfile is determined by DHCP, when missing. 121For wd it defaults to "netbsd". 122For mem the bootfile is actually a hexadecimal address to load from and 123is mandatory. 124 125 ### ### ### 126