| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | Information about the Linux/PPC kernel images | 
|  | 2 | ===================================================================== | 
|  | 3 |  | 
|  | 4 | Please mail me (Cort Dougan, cort@fsmlabs.com) if you have questions, | 
|  | 5 | comments or corrections. | 
|  | 6 |  | 
|  | 7 | This document is meant to answer several questions I've had about how | 
|  | 8 | the PReP system boots and how Linux/PPC interacts with that mechanism. | 
|  | 9 | It would be nice if we could have information on how other architectures | 
|  | 10 | boot here as well.  If you have anything to contribute, please | 
|  | 11 | let me know. | 
|  | 12 |  | 
|  | 13 |  | 
|  | 14 | 1. PReP boot file | 
|  | 15 |  | 
|  | 16 | This is the file necessary to boot PReP systems from floppy or | 
|  | 17 | hard drive.  The firmware reads the PReP partition table entry | 
|  | 18 | and will load the image accordingly. | 
|  | 19 |  | 
|  | 20 | To boot the zImage, copy it onto a floppy with dd if=zImage of=/dev/fd0h1440 | 
|  | 21 | or onto a PReP hard drive partition with dd if=zImage of=/dev/sda4 | 
|  | 22 | assuming you've created a PReP partition (type 0x41) with fdisk on | 
|  | 23 | /dev/sda4. | 
|  | 24 |  | 
|  | 25 | The layout of the image format is: | 
|  | 26 |  | 
|  | 27 | 0x0     +------------+ | 
|  | 28 | |            | PReP partition table entry | 
|  | 29 | |            | | 
|  | 30 | 0x400   +------------+ | 
|  | 31 | |            | Bootstrap program code + data | 
|  | 32 | |            | | 
|  | 33 | |            | | 
|  | 34 | +------------+ | 
|  | 35 | |            | compressed kernel, elf header removed | 
|  | 36 | +------------+ | 
|  | 37 | |            | initrd (if loaded) | 
|  | 38 | +------------+ | 
|  | 39 | |            | Elf section table for bootstrap program | 
|  | 40 | +------------+ | 
|  | 41 |  | 
|  | 42 |  | 
|  | 43 | 2. MBX boot file | 
|  | 44 |  | 
|  | 45 | The MBX boards can load an elf image, and relocate it to the | 
|  | 46 | proper location in memory - it copies the image to the location it was | 
|  | 47 | linked at. |