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From: "Guillaume Dargaud" <dargaud@lpsc.in2p3.fr>
To: "ppcdev" <linuxppc-dev@ozlabs.org>
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Subject: Re: Calling the kernel from a mini-bootloader
Date: Tue, 22 Jul 2008 12:49:49 +0200
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Thank you Milton for the detailed explanation. It'll take me quite a while 
to digest it.


As a follow up to my previous messages, I now have a working kernel and a 
working bootloader... but not when they are both together.

Case in point:
- load zImage.elf to DRAM 0x400000 with JTAG debugger. Run it. It runs fine.

- Load Bootloader.elf to BRAM 0xFFFF0000 with JTAG debugger. Run it. It runs 
fine (but it doesn't do much yet).

- Now load both of the previous ones, and have the bootloader perform a jump 
to kernel:
     typedef void tFunc(void);
     ((tFunc *)0x400000)();

The kernel seems to start:

loaded at:     00400000 004EA19C
board data at: 004E8120 004E819C
relocated to:  0040405C 004040D8
zimage at:     00404E48 004E7A7E
avail ram:     004EB000 08000000

Linux/PPC load: console=ttyUL0,115200 rw root=/dev/nfs ip=bootp
Uncompressing Linux...done.
Now booting the kernel

But then it hangs for exactly 3 minutes, nothing on the serial port, before 
the bootloader restarts.
Why should the behavior be different whether it's started from the debugger 
or from my bootloader ?
-- 
Guillaume Dargaud
http://www.gdargaud.net/