[ARMedslack] A quick primer for the PI

[dowelld at netscape.net]

-----Original Message-----

From: Davide <louigi600 at yahoo.it>
To: Slackware ARM port <armedslack at lists.armedslack.org>
Sent: Wed, Sep 25, 2013 3:46 pm
Subject: [ARMedslack] A quick primer for the PI






I got a friend to lend me a PI  for a week ...
I had a quick look at the community links for slackware on the PI but none really tell me what i want to know:
what does the GPU  look  for in the SD ? (as fas as I know it's the GPU that loads stuff from SD into memory and then passes control to it)
does it look for a second stage boot loader like a uboot image or does it load kernel and initrd ? (bootcode.bin)
I'm supposing that the first partition (the dos one) is where this stuff should be put ?
The content in there looks about right:

root at darkstar:/tmp# fdisk  -l slackwarearm-14.0-8GB-20130623.img 

Disk slackwarearm-14.0-8GB-20130623.img: 2558 MB, 2558967808 bytes
4 heads, 32 sectors/track, 39046 cylinders, total 4997984 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00007091

                             Device Boot      Start         End      Blocks   Id  System
slackwarearm-14.0-8GB-20130623.img1              32       97663       48816    c  W95 FAT32 (LBA)
slackwarearm-14.0-8GB-20130623.img2           97664      878847      390592   82  Linux swap
slackwarearm-14.0-8GB-20130623.img3          878848    15751167     7436160   83  Linux
root at darkstar:/tmp# echo $((32 * 512))
16384
root at darkstar:/tmp# losetup -o 16384 /dev/loop0  slackwarearm-14.0-8GB-20130623.img
root at darkstar:/tmp# modprobe vfat
root at darkstar:/tmp# mount /dev/loop0 /mnt/floppy/
root at darkstar:/tmp# ls /mnt/floppy/
COPYING.linux*                  config-raspberrypi-3.2.27*  start.elf*
LICENCE.broadcom*               config.txt*                 start_cd.elf*
System.map-raspberrypi-3.2.27*  fixup.dat*                  zImage-raspberrypi-3.2.27*
bootcode.bin*                   fixup_cd.dat*
cmdline.txt*                    initrd-raspberrypi.img*
root at darkstar:/tmp#


I plan to play a little with a miniroot so I won't need an 8Gb SD :)

ATB
David


Hi David,

The GPU looks for bootcode.bin, which looks for and loads loader.bin. Loader.bin reads in config.txt (to configure the hardware) and loads start.elf (the GPU binary blob). Once it has configured the hardware, it then loads kernel.img, and feeds it the contents of cmdline.txt.

So you have to have bootcode.bin, loader.bin, config.txt, start.elf, kernel.img, and cmdline.txt, then if you load a ramdisk image in the cmdline.txt file you need the ramdisk image file.

Thanks
Dave

 

 




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