README.ipl revision 1.1.4.2
1 1.1.4.2 rmind # $NetBSD: README.ipl,v 1.1.4.2 2014/05/18 17:45:11 rmind Exp $ 2 1.1.4.2 rmind 3 1.1.4.2 rmind Coding note: 4 1.1.4.2 rmind 5 1.1.4.2 rmind In order to make this relocatable, you must follow following 6 1.1.4.2 rmind restrictions: 7 1.1.4.2 rmind 8 1.1.4.2 rmind 1. Do not place any objects in text segment 9 1.1.4.2 rmind 1.1. For compiler, 10 1.1.4.2 rmind (1) do not declare or define any objects to be placed in 11 1.1.4.2 rmind text segment, that is, do not use ``const'' keyword 12 1.1.4.2 rmind (but declaring a pointer to const is probably OK), 13 1.1.4.2 rmind 14 1.1.4.2 rmind (2) make sure string literals, if any, are placed in data 15 1.1.4.2 rmind segment (use traditional compiler), 16 1.1.4.2 rmind 17 1.1.4.2 rmind (3) avoid initialization of automatic objects (non-static 18 1.1.4.2 rmind function-local variables) of aggregate types (arrays, 19 1.1.4.2 rmind structs and unions), which may implicitly emits 20 1.1.4.2 rmind constant data. 21 1.1.4.2 rmind 22 1.1.4.2 rmind In summary, do not use ANSI extension. Use traditional C. :-) 23 1.1.4.2 rmind 24 1.1.4.2 rmind 1.2. For linker, do not actually place objects in text segment. 25 1.1.4.2 rmind 26 1.1.4.2 rmind 2. Do not use function pointers. 27 1.1.4.2 rmind 28 1.1.4.2 rmind 29 1.1.4.2 rmind On-disk layout: 30 1.1.4.2 rmind 31 1.1.4.2 rmind We have 6.5KB for the primary boot. 32 1.1.4.2 rmind 33 1.1.4.2 rmind disk address 34 1.1.4.2 rmind start size 35 1.1.4.2 rmind 000000 0000FC LIF header 36 1.1.4.2 rmind 0000FC 000104 unused 37 1.1.4.2 rmind 000200 000194 disklabel (404 bytes for 16-partition label) 38 1.1.4.2 rmind 000394 00006C unused 39 1.1.4.2 rmind 000400 000400 ipl part 2 (1KB) 40 1.1.4.2 rmind 000800 000100 optional LIF directory 41 1.1.4.2 rmind 000900 000100 unused 42 1.1.4.2 rmind 000A00 000600 ipl part 3 (1.5KB) 43 1.1.4.2 rmind 001000 001000 ipl part 1 (4KB) 44 1.1.4.2 rmind 002000 (file system starts here) 45 1.1.4.2 rmind 46 1.1.4.2 rmind 47 1.1.4.2 rmind On-memory layout on IPL startup: 48 1.1.4.2 rmind 49 1.1.4.2 rmind The firmware loads ipl part 1 on the memory, and executes it. 50 1.1.4.2 rmind 51 1.1.4.2 rmind address offset 52 1.1.4.2 rmind start size 53 1.1.4.2 rmind 000000 001000 ipl part 1 54 1.1.4.2 rmind 001000 000A00 (not loaded yet) 55 1.1.4.2 rmind (bss section etc) 56 1.1.4.2 rmind x 001000 temporary disk buffer 57 1.1.4.2 rmind x+1000 stack 58 1.1.4.2 rmind 59 1.1.4.2 rmind 60 1.1.4.2 rmind Then the IPL will load the rest of itself: 61 1.1.4.2 rmind 62 1.1.4.2 rmind ipl part 1 loads parts 2 and 3, then continues execution. 63 1.1.4.2 rmind 64 1.1.4.2 rmind address offset 65 1.1.4.2 rmind start size 66 1.1.4.2 rmind 000000 001000 ipl part 1 67 1.1.4.2 rmind 001000 000400 ipl part 2 68 1.1.4.2 rmind 001400 000600 ipl part 3 69 1.1.4.2 rmind 001A00 xxxxxx (bss section etc) 70
Indexes created Fri Oct 31 04:09:52 GMT 2025